You just be firm.

If you're so into threesome, you should've made CLEAR ground rules. One of them is that the other person shouldn't be someone you both have to deal with on a daily basis.
And at least, you should be able to STAND or find the other person acceptable or have the potential of good sexual experience (not to mention you all have to get tested before doing the deed, and etc, if you ALL agreed).

Tell him that if he insisted with her, and since you don't like her, you WILL NOT ENJOY the experience at all and will hold that over his head for as long as you both last in this relationship, and not to mention that: there will not be a threesome too if he chose that girl. How the heck can you enjoy yourself if you don't like the girl at all? LOL, seriously, he needs to get unselfish and vice versa if he finds the boy you chose to be annoying.

Hey, at least you know that he's kind of crushing on the girl you're weary of. And if he's a jerk, he'd break up with you or be mean to you, then you'd know if he's someone you want to have around or not anymore.

Frankly, I would advice against the threesome completely...but just say no to that chick and make him choose another...if you're going to get into it, you both have to agree on the outside victim...errr extra partner.

Tell him you've decided it's a horrible idea and drop the subject. Don't be surprised if you've done permanent damage already though.

Tell him that he gets to choose the guy and you get to choose the girl, that should be the FIRST ground rule for something like this. You dont want her in your bed, simple as that, he is disrespecting you completely by insisting otherwise!! If I was in this situation and my boyfriend acted so insensitively I would flip out. Tell him the bottom line is you dont want her to be involved and you are having major second thoughts on the whole thing because of how he is reacting to your comfort levels.

A threesome should be about fun and trust and safety, not insecurities and jealousy and fear. You and your boyfriend obviously need to go back to step one and re-evaluate each others' needs on this subject and set straight ground rules. Rule #1: You both must be 100% comfortable with the 3rd person. No ifs, ands or buts. You both must 100% agree, no hesitation.

Good luck and be careful.

Personally, I think it's not a good idea. Again, personally speaking, I'd never have threesome with someone I love because I know I'll end up feeling jealous.

This is one instance where the sharing rule is in-effective. I have never and will never share my man. You never know if maybe just maybe he starts falling for that "third-wheel". You think they would never cheat on you but when YOU allow the extra tail in the bed... it's your own fault if he gets snatched. Don't do it girl.

Tell him that you are not comfortable having the other girl involved in your sex life. I wouldn't be so concerned about 'going back on your word'. You are in a relationship, and if you want to do something as intimate as having sex with another person, both of you should be comfortable with it. That is all you have to say to him. This is the reason why threesomes are never a good idea when 2 of the people are involved in a relationship. Someone will always feel either left out or jealous. If your guy cannot respect your decision, then maybe he doesn't really respect you.

BTW, my sister had a threesome with her friend and her husband. You can guess how that turned out. Her husband started having an affair with the other woman, and he left my sister for her. She was absolutely devastated for years afterwards. A threesome is a nice fantasy, but never very nice in reality. Sometimes fantasies should just be kept as fantasies.

what's the worst that could happen by you telling him? if he can't forgive you, your relationship may be doomed. but if you go through with it without actually wanting to, then your relationship will be doomed anyway. just tell him.

He's your boyfriend, I'm sure he doesn't want you to be uncomfortable or unhappy. Tell him you're not comfortable with his choice, and he can pick another girl (like someone else said, it should be one neither of you has to see on a daily basis) or call the whole thing off.

Fantasies and reality are two very different things. What might seem great in your fantasy often turns out quite the opposite in reality because life is just so much more complicated. Before you consider anything else I think you should keep that in mind and really ask yourself if you enjoy the fantasy but now when things are getting serious you are not sure if you really want a threesome or not.
Once you've decided that for yourself and you still want to go ahead with a threesome, just not with this particular woman, you have to tell your bf. And he has no right to get mad or upset because this is suppose to be good for both of you and if one of you is not comfortable with the third person then it will never work.

That said in most cases threesomes never work out because it's usually just one person that really wants it and the his or her partner goes along because he is afraid to lose them. I'm not saying this is the case with you but it is something to think about and in a relationship you should never do something you don't really want just to make the other one happy, especially not when it comes to sex.

Its really hard for me to give good advice here because personally I could never see myself in a threesome. Fantasies, sure - but reality is these situations can create so many complex, tangled-up, messy emotional situations afterwards...situations I would hope to never be in myself.

There's a few things that concern me here:

1)Taking a step like that in a relationship is a massive one. Its all well and good to talk about it, but as someone said above, ground rules HAVE TO BE LAID down, well and clearly - and maybe that should have included "nobody we work with", etc.

2)It would wig me out a bit too that he does work with the girl he's chosen, and has daily contact with her. But then again, if you cannot trust him to be around her to begin with, you guys had no business entering into a threesome. That really seems to require either absolute trust and understanding, or absolute lack of concern as to the consequences - neither of which apply here.

3)If you explain to him that you have thought about it, and have realized you have issues with it and found yourself feeling jealous instead of positive - he SHOULD be supportive of that, hopefully, and it will be an issue laid to rest and confined to fantasies. If he gets angry - then my dear, you've got another problem besides threesomes to worry about.

4)Try to come up with alternative fantasy ideas to "soften the blow" if you feel this will really be a setback between you. Perhaps that will derail the threesome idea and give you guys a new focus that is healthier for you at this time.

Good luck either way.

easy. you don't get YOUR threesome. He doesn't get HIS.
I'm sure most guys are uncomfortable having sex especially when another MAN is naked in the same room, but if he's willing to make your fantasy come true, suck it up and make his happen. or just don't do it at all.

jealousy is the reason i will NEVER...EVER have a threesome. Chances are, I'll punch the other persons lights out.

any man who is willing to have anothers guys peener next to him and it not be in a gym? has issues. run for the hills.

Respect yourself and dont ever agree to do a threesome again.

I can't believe this is even a question. If you are not into it, OF COURSE you tell your boyfriend that you have changed your mind! We are human, we change our minds all the time, and you should never, ever, EVER do something because you feel pressured into it. And if your guy is the type that will "never forgive" you for "going back on your word" in this type of situation ... well... you have a lot to think about regarding staying in that relationship.

Threesomes are fun, trust me I have had my fair share. But I would never, never do it with some one I was in a serious relationship with. I think it would just mess all sorts of things up, and there would be some trust issues once it was done.

CaterpillarGirl thats not true. Two women can be completely naked beside each other and making out but they can still be straight. Just like two guys can be banging the same woman at the same time and still not be attracted to each other. Guys who are confident in their sexuality realize that just because there's a naked man in the room doenst mean their gay, bi or "has issues"

That's why threesomes are always a great thing to fantasize about. I think if you really want to follow through with a threesome though, you should pick the girl.

Um, he works with her, are you ready to handle the repercussions it will have on your relationship? This ins't something for nothing, you know. Don't do it.

I think Id be a little concerned if he was willing to have a threesome with another guy too...I know that it may not reflect on his confidence in his masculinity or something but still...it is creepy. Then again I am not the type to have threesomes and neither is my boyfriend.

I am a Scorpio, and I would be too jealous, no matter who picked the girl. I would rather channel that energy into finding other ways to enjoy each other, sexually and otherwise.

I think if you want to experience a threesome, it should not be with someone you want a long term relationship with...I personally could not let it go of it and would always be wondering if he was thinking about someone else besides me.

The fact that you are having doubts automatically puts you in the Don't Do It category... you will always resent it if you do it just for him.

This is strange, girlfriend go online and find a random girl or hire a prostitute. What you are describing is a bad idea. It will ruin both of You

^ In other words she should go STD shopping, LOLZ.

i would get soo jealous if my boyfriend picked another woman.. i feel like YOU should pick the woman and he should be happy with that choice instead of basically saying.. "i want to have sex with this woman i work with even though you are my girlfriend.."

just back out. if he loves you, he will understand. your feelings are much more important than his desire to have sex with another woman. if he gets mad at you, he's a very selfish man.

Fallen, that is straight out of guys that i know mouths, so it might not be true for your guy friends but it is for mine. and I will add that if a guy IS okay with that? he can stay away from me.

You really ought to be able to talk something like this out with him. If you can't, it is already a reflection of your relationship. When you're new to a multiple partners situation, it takes a lot of talk and a lot of figuring out how to work it into what you already have. Both of you have to be willing to say exactly what you think about it at all times.

I didn't mean she should go STD shopping !!!! NO way, you can still have fun and be safe. Prostitutes do not equal STD!!! what a horrible to say about prostitutes, i have nothing against the profession. It's a service. that's all.

LoL, fine, well I guess happy sex shopping, just make sure the prostitutes or escorts have a medical records. I'm actually against sex selling since there's too many issues and instances of exploitation for my taste. (Other than I'm not really into buying sex when I could get it for free with someone I love).

O, and there's some STDs out there that you won't even know you have. And that goes especially for guys considering they don't have pap smears for us males.

If he never forgives you for going back on your word to have sex with another person, what kind of a relationship are you in??? Honestly, I don't understand how you can love someone and want to share lovemaking with a third party. God knows I'm no prude, and I've had a 3some - but not with MY BOYFRIEND! Eeeeew. I could never get over seeing him laying his hands on another woman's body. And suddenly, it looks like the reality of it is striking you too. Fantasies are good as fantasies. Bringing them in the bedroom is a whole new ballgame; it can get so incredibly messy and destructive. Talk to him in those terms; you were wrong, and you need to bury this. Hopefully you can laugh about it some day, but I think the damage's been done : now you know he wants to have sex with that girl, and it will NEVER get out of your head.

Good luck with that.

Would you ask for a medical record when you see a hot girl who is willing to do a one night stand? Most men would say NO. You use condom and you don't do oral sex. Same rules apply to prostitutes. But anyway never mind.

I really don't know were to start b/c I've been through this conversation with my man numerouse of time's. When we got together he informed me that he was down with threesomes and any other fantasies that I would like to try! For the first 4 months we were good but when he started working with women that were willing to try us both on for size I wasn't feeling it! We talked about it more than once b/c I informed him that I was a jealousy women! The day came around when we tried it and I was ok with it until I noticed him giving her more attention than me. I know your suppose to enjoy it but how can you do that when your use to having him all to your self!
Once we completed the fantasies I was feeling a little upset. We discussed what just happened but I don't think he was understanding my point of view. It took at least a week for me to get over the hurt that I was feeling from his misunderstanding. After we took time out from this situation he ask me would I like to try it again and I bluntly said no! I felt I wasn't ready for that type of action just b/c I was a very jealousy women!
The point that I am trying to make is that you have to decide if this is what you want! If he's informing you that this women is who he would like to try then that should ring a bell for you. Maybe him and this women might have discussed some thing's while at work or done some flirting along the way! When your in a serious relationship it's not best b/c I wouldn't want nothing said later on in the relationship! If he's not willing to change then maybe he's not the right person for you b/c when marriage comes along there is no threesomes unless you can discuss the problem!

LoL, I'm wary of woman who are so quick to hop in the sec, especially since condoms are only 85% effective. I'd rather be safe, but to each his own. Doesn't matter anyway, everyone lives the way they want. Whatever happens everyone must deal with their own consequences, whether it be a onesome or a threesome, or mass orgy.

you should pick the girl! This has always been my rule for a 2 girl 1 male threesome. I pick her! Right now, he is asking you permission to sleep with a coworker! That is... wrong, imo. It should be someone that you are 100% comfortable with and if you're not with her, then tell him.

If you seriously thought about a threesome before then I wouldn't rule it out altogether, perhaps just say that she isn't the right one and keep looking.

Well, if it's just sex, it should matter who the chick is right, so why should he have a problem picking someone else? Haha, bingo! It's not JUST sex!

hmmmm....as a person who has parcipated in a threesome before....THINK REALLY HARD...before doing it. sure it can be a great fantasy.....but think about your emotional being when it will all be done. can and will you be able to handle it? will you feel guilty? will your boyfriend? and if you choose to go thru with it...you both need to agree on partners or it won't work. then you ALL need to set ground rules...some people prefer that you don't kiss the other's partner or have oral sex or anal with them. think long and hard.....in the end it may destory your relationship with him or heighten it...

shadowdamage has some great points.
its okay if you don't want to do it anymore, better you realized that this may not be as good of an idea now than later. you really need to discuss it with your boyfriend. if you are feeling at all uncomfortable it is important to tell him and explain why even if you think he might be confused or upset at first. i think as long as you are honest and sincere he should be understanding about it, as he is your boyfriend (someone you can and should be honest and comfortable with).

on a separate note, the coworker thing sounds a little strange to me. how does he know about her sexual experiences? i think that is a little strange, but i don't want to assume anything. i can't help but find it a little inappropriate that he would bring someone into the bedroom with you that is not only someone that you don't gel well with(if you had told him how you feel about her before this), but a coworker that he sees on a daily basis. choosing her based solely on the fact that she has had threesomes before is not enough for me. he might be "comfortable" enough with her, but that doesn't mean you have to be.

i would be really concerned about the status of my relationship if we were both shopping around for new people to screw! if he's comfortable watching another man F-ing you then i don't know..I've never been in a relationship where this has even come up.

One of my best friends was in a long-term relationship that was reaching its end and they decided to go out and each meet someone new to go home with. She ended up sleeping with two men in one night and he didn't find anyone and went crazy on her. another time they "picked up" a couple (the girl was a friend of ours from high school) and did a swap. this is DANGEROUS TERRITORY!!!

Tell him how you feel. If he cares about you AT ALL, he'll drop it immediately and move forward. If he doesn't, leave him.

i have to say that if you don't feel comfortable with the circumstances, in any way - then you need to tell him and get yourself out of that. i don't think that this could lead to anything good for either of you. regardless that it's a three some and not one on one, you have to remember that you're involved in this highly personal sex act and that your man is doing the same - so you need to tell him that you're NOT into it.