Why doesn't he ever finish?

Theres this guy, he's not my boyfriend, it's more of fwb if anything I guess. We had for the 1st time and we were both pretty buzzed, he never finished though, he asked what time it was and said he had to go. The 2nd time we had the same thing happened, and last time it happened too. I don't know why he always needs to leave in the middle of it. He always will say stuff like he'll be back, nd we'll finish but it just never seems to happen I guess. Is this weird at all? None of the other guys i've had with have done this..