Why do you......

Okay so where to start.......
I have been talking to this guys since me and my boyfriend broke up, but flip side my (ex)boyfriend wants us to work our problems out. Work on us... Right you want to work on us after I decide to leave. Anyway back to the story so we get kinda close and we enjoy the time we spend with each other. So we hang out when ever he gets time, which is very rare. So I hang out with other guys but I don't have a connection with any of them like I do with this other guy. I respect the unique relationship (if I can call it that) I have with him. So I tell him when I do hang out with other guys so it doesn't seem like I am lying to him. So Thanksgiving came around and I didn't see or hear from him all day, so I went out with a good friend. I tell him the next time I talk to him and he says okay. So like couple weeks go past and he sends me a late text telling me that he was semi jealous of the fact that spent a whole weekend with another man...... What in the hell!!!!! When he is given the opportunity he doesn't take it but he gets upset when I still try to have a life outside that I had before him. What is it with men???? It is not like I am dating these other guys they are just male friends nothing more....