"My boyfriend wants a threesome with another girl. I'm interested but unsure of the aftermath."
I'm inexperienced at sex, only two years out of a long marriage and bi-curious. My boyfriend of two months is older, very experienced, confident and has tried swinging and just about everything else.
He's as keen as me to have a girl-on-girl sex session but he wants it to involve him as well. I know this sounds insecure but I am worried he will fancy her more or she will be more experienced and it will change our relationship and how I see him.
I'm turned on by the thought of him being involved but unsure of the aftermath. Help!
I would tread very carefully about putting this fantasy into practice with your boyfriend. Threesomes are up there with everyone's top fantasy turn-on, but in reality tend to go very, very wrong for the very reasons you're suggesting.
Three is an odd number - one person is invariably left out and that doesn't feel quite so hot. If he starts paying a lot of attention to the girl, it's natural to feel jealous. And yes, it's entirely possible you will worry afterwards whether he enjoyed sex with her more or even wants to see her again.
Threesomes work best when the people involved aren't emotionally attached to each other. They are incredibly dangerous emotionally for people who are.
I've seen them break up many a good relationship and you need to be a very confident, secure person to deal with them. You say you aren't very experienced and don't feel confident and already feel on the back foot.
If you want a girl-on-girl experience, have it solo. That way you can enjoy the experience without worrying about the consequences. If you then want to include him another time, when you have more confidence, do it then.
If he's as cool about sexual experimentation as you say he is, he will understand. If he doesn't and insists you do it with him, he's out for kicks rather than wanting you to explore new experiences safely.