OK, after seeing how long and drawn out my other posts have been I'll try to keep this shorter..but no promises.

First of all, Missy, if this is something that you're not into then absolutely don't do it.

Part of the enjoyment of sex is the fact that everyone gets pleasure from it not juts one person. Besides, even if you do decide to do it to make your boyfriend happy, (which will make you resent him down the line), the other girl will be able to pick up that you're not really into what she's doing so it would be nothing more than a disappointment for her as well.

My advice to you, whether its good bad or indifferent, would be to clearly tell him that girl/girl sex is something you are no more into than he is having guy/guy sex and that you have no desire to try. Also, let him know that his constant topic broaching is annoying (if it is) and ask him to kindly refrain from it.

One way that you could possibly skip the actual girl/girl sex part, while assisting in his fantasy, is to do what I have done in the past, ( not so much from my not wanting to have sex with another woman but just not having one available). If you're comfortable with the idea, while the two of you are playing, you can describe what you would be doing if another girl were there. I did this with an old boyfriend of mine who was absolutely insane over the idea of watching me with another woman and it kept him happy for months.

But most of all...dont do anything you arent comfortable doing.