My male friend is hiding an issue from me? Why would he do that?

Me and my guy friend have been close for years now. He tells me everything, I tell him everything. He recently set me up with a girl I didn’t know too well (he believes we can’t be together cause he’s moving out of state soon) and has been acting depressed and solemn since he put us together. Now he refuses to tell me specifically (he literally told me he wasn’t gonna tell *me* why, not anyone else) why he’s not okay and I’m not pressing him about the issue further but I just want to know why a guy wouldn’t just say that he wanted us to be together. Why he would set us up in a thruple but when I push him out of the relationship to give us a chance to get to know each other a bit better he gets angry with her and sad and solemn around me. Is he jealous? I feel the same about him, we’ve been in a convoluted, semi-serious friends with benefits arrangement recently and we started talking about kids and settling down together… wtf is going on?

My male friend is hiding an issue from me? Why would he do that?
Post Opinion