My FWB wants to hang out?

so my FWB wants to hang out like movies, eating out on top of as well. BUt, i know he will be boinking other people as well. I dont want to spend my quality time with him eating out and movies or just hanging when i know he is probably doing all that with other people as well. WHat shud i do? shud i just tell him like it is "i dont wanna spend quality time with you when you are boinking other people..." It is nice that he wants that but what bothers me is that he will be boinking other people and spending qualtiy time with me?? does that makes sense? Help what shud i do?