male advice needed asap?!?

basically my relationship of 8 months is going down hill after i hear he saw his ex when she came in town (he denies it), he has a promise ring...but he goes from finding a job to be where i stay, to not wanting to do that...not feeling the relationship, wanting to do"what he wants to do", my attraction is decreasing to him and he's not sure if hes 100 percent if he's in love with me. then he turns around and apologizes for talking and treating me like crap...only to do it again this week. he says"if i left him he wouldnt even shed a tear"and other mean things like that..then turns around to say he is going to"act right"n he does want to see me this weekend...what is going on? im 20 he is 21

I would leave him...He's obviously having some kind of crisis in his life. Tell him unless he's ready to control his emotions and stop treating you badly that then your gone, and even leave for a night or 2 to see how he reacts.Hope this helps.