Why would my FWB be jealous over me?

Anonymous
See, I've got this guy whom I've been FWB with for almost 2 years now. Anytime he knows I'm hanging out or hooking up with other men he gets REALLY jealous and gets mad at me. Why would he be doing this? He has a girlfriend and has other women too and I'm not jealous over that. I am actually very happy being single. Could it be he's insecure about possibly losing me? He's 16 yrs. younger than me. Does he possibly have more feelings for me he's not wanting to admit to? Or does he just want me to only be with just him? We have such hot passionate sex when we do get together except he doesn't like to kiss and that bothers me a lot as I absolutely love kissing especially him and he knows it. (Which has been about 3 times or more a week for the past few months now.) What should I do? I tried to ask him why he's jealous and he denies he is. I told him he gives me very dirty looks and then refuses to talk to me for a little bit if he knows I've been around other men. (Even if NOTHING is going on between me and the other men) Then if we end up having sex shortly after he shows his jealousy it's awesome sex too. I'm about to end the FWB with him as he doesn't show me enough respect and I've caught him in too many lies lately over simple little things. So what's everyone's opinion about this situation?
Why would my FWB be jealous over me?
4 Opinion