Why is he getting jealous about hanging out with male friends?

Ashley

My boyfriend and I broke up. I'm still in contact with him, the other day I picked his friend up from work, I didn't wait for him to come out, he called and was jealous that I was out with a couple of his friends.

Then his friend that I picked up from work was like, "if he knew we were hanging out right now, he'd be pissed. He says he doesn't care, but acts otherwise."