Have you been in a half ass relationship?

I feel like I'm in a half ass relationship. When your other half isn't giving their 100% effort into the relationship. It's hard for me to believe him when he says he loves me & cares about me. I just rarely feel important enough for him most of the time. This is my longest relationship. But i feel like I'm young, & i shouldn't be trying to have a serious relationship. I already fell in love with him though so it's hard for me to just leave.