My SO and I want to have a threesome with another girl. We have been on some dating apps trying find a contender and a few times he has mentioned a person that we know. One of my coworkers specifically. Also one of his clients that he tattoos. I've told him I don't feel comfortable with it and i would rather it be someone we don't know too well or have a friendship with. That's just my comfort level right now. I'm sure it could eventually change. He, however, thinks that I'm trying to make up excuses for it to not happen. This always ends up in an argument. I'm just wondering is this a common boundary people have or am I subconsciously trying to make this not happen? I've always been bicurious and the thought of a threesome sounds fun/hot. But there's certain people I would just rather not with