How far would you go?

If you are bisexual and want a threesome with another woman, how far would you let boyfriend go with her (he's a long-term boyfriend and I am never jealous of anything, but I don't think I like to see him go all the way...^^ and I would never pursue a...

relationship behind his back either with her)

Ask your boyfriend. If he really loves you, and you really love him... He wont want to share you. Even if its another woman. And you wouldnt want to disrespect him.

If you want this relationship to last, maybe be the Real Thing, do not do this at all. You are going down a path that will destroy your relationship. This is just the same as cheating on your lover, but with his permission. Very problematic. There will be guilt, jealousy, and resentment - possibly from both of you.
Unless you and your boyfriend are both sex addicts. Then this would support both of your illnesses.

If however you are young adults - late teens, early twenties - and you just want to have fun and are not worried about your relationship lasting, then go ahead and enjoy.

if you feel it will ruin the relationship then don't do it...I want a 3 way with my girlfriend and another chick but she wont...she told me if we had 1 with another guy I would but I said no...after thinking about it I thought what the hell and said I would do it with another girl...ok a few things could happen if you's do go through with it...1 like stated above...1 of the party could get jelous...2 if you decide to do it with a friend...it might become awkward to talk to them afterwords...my advice is tho if you do choose to go through with it...hire a escort... you wont have to worry about her ever coming back..they are there to do a job and nothing else..they have weekly hiv/herps/clap check ups at the doctors...but before you even think about that.,...watch a porno movie with him and see how you feel about him looking at other naked girls getting aroused...if you get horny watching it to then you might be ok but if you just feel like your not good enough if he is really getting into the movie...then steer right away from the 3 way cause it will most likely end badly. hope all works out for you guys

if your not comfortable with it, dont do it
I wouldnt want a threesome in the first place but I dont think he should go any further than oral with her
also make sure the other girl isnt a friend
if your going to have a threesome, do I with a girl that your both not friends with
quite a lot of people break up if a friend ends up involved