What does it mean when a guy says he has strong feelings for you?

I've been talking to this guy for three months. He calls me every night and text me every morning. He goes to school five hrs away but when he comes home he spends time with me. He came home this past weekend and told me he wanted to tell me that he has strong feelings for me. I asked him to elaborate and he was stubborn and wouldn't. He is not my boyfriend. I'm still trying figure out what's taking him so long. Someone please help me out!