>>936289875 (OP)
A bit of a long story:
I had a girl who I've been seeing for sex. Friends with benefits. She was open about it and told me she was seeing some other guys.
Once when I called her, she said she had a boyfriend and didn't want to see me. I respected that.
But after a while she called me again, but this time to stop by. We had sex and then she left immediately.
I thought she broke up with her boyfriend.
The reality is that her boyfriend has become one of the guys she's been seeing before. At first she thought that they are going to have classic relationship. But he wanted her to continue having sex with other men.
After that, I stopped by to fuck her at his apartment. She didn't like having sex with more than one guy, but she really liked having sex one by one in a row.