I'd love to move on but I can't :(?

I called my boyfriend not too long ago and told him that I just can't find enough reasons to stay with him. But he always has me so convinced that he will change. I have people on here telling me that him grabbing me is a sign of abuse but I'm not too sure if it is. I mean it was a grab but it was because I was wanting to leave and go home after an argument and he got really mad. When he's mad me says " look at me " and forces my face to look into his eyes and then says " I didn't mean it like that " or anything to cover up what he did. He convinces me a lot but I do feel like nothing is happening at the same time. I need some positive advice to tell me, maybe he is the right guy? We don't go out that much and we've been dating for 4 months. I'm glad I have my daycare that I attend because seeing children smile makes my day but when I see him I just get all that positive energy to a negative because we either are arguing about his attitude. It's stressful but he is a good guy. I know deep down he could possibly change with some work but every time he says he will change he doesn't. Although this time he said to give him ONE more chance :( Could he possibly change his attitude in his voice? could he be more nicer to me EVERYDAY rather then the days when he knows he's done something wrong? Could he take me out more and be more fun? Could he lose his temper and become more nice? I'd love some positive encouraging words, I am just so confused. Some days I see myself with him for a lifetime and other times I don't.