Ofcourse he is suspicious.
"Yeah, you just go and fuck whomever you want. I don't really care either way."
Jealousy, in moderation, shows a person you care. It shows that you care enough about them to be afraid of losing them, and think they are an attractive enough partner to make others want to steal them away. What it also shows is that you are against cheating, and would not want it to happen to you. Someone who understands why you don't want them to fuck others because of having the exact same feeling seems much more likely to not cheat.
When a woman tells me she's ok with me fucking other women, I'll assume she's doing the same thing
