because they dont want anyone else to have their lover, but goes out and has sex with others without their lover knowing.
So someone being protective or jealous or controlling in not sharing their lover with someone else, but then to go on and have an affair privately? Doesn't make sense to me at all. So that's like saying I can have you, but no one else can. But if I want someone else, that's ok for me? Just not ok for you? Very selfish.
I have before. I'm not saying what I did was right. But, I'm not interested in a three some. My partner due to medical conditions wasn't interested in having sex. I went a year and a half without having sex and I became weak. I gave in to a long time temptation and I don't regret it. The lack of sex and feeling of being sexually desired pushed me into someone else's arms. I would be hurt if that partner had gone out and had sex with someone else because then the true issue at hand would have been me and his capacity of being attracted to me or not. I don't think this made me selfish. I think this made me human and the desire to be wanted became too much for me.