Just a curious question really... What is it that makes guys so hot when watching their girls with another man? My other half has never mentioned it to me and we're pretty open...
For some people, watching your partner can be extremely sexy for a few different reasons. Some people enjoy the voyeurism of the experience as it can feel like you are seeing something very intimate that few people get to see. It is taboo and feels naughty as you are experiencing your partner, who you are familiar with, in an unfamiliar situation. There is also the simple visual stimulation that you can see your partners body in a different way. I have personally never tried it but I have thought about it many times.
I actually asked a partner who mentioned it briefly,and in heat of the moment. He's done a few threesomes as the outsider. Seems he wants to see how I would react to another. It isn't all that important to him. We are not pursuing it by any means. But he does like exhibitionistic stuff in consenting situations (say at a motel with a scene, not random)
I don't get it either. I find the very thought revolting. I mean, the way women who have steady partners act with me at the parties, I'm horrified that my girlfriend might act like that when I'm not around. As to her actually having sex with another man... I would totally blow my top. But then again, there are people who enjoy getting whipped, or drinking urine, and whatever.