Advice please

My boyfriend seems really distant lately, we live 2 hours apart and it seems like he never wants to take time to call or text me. I usually have to first. It's very frustrating for me, and I try to talk to him about it but he just says I have no reason to be upset and blows me off. When we are together though he doesn't act like that at all and tells me he loves me constantly. I love him and I don't want to lose him but this is really making me unhappy, and I don't want to tell him because I know he will just get mad. Please help me out with some advice as to what to do?! :(