Is it love or not?

I am in a relationship with a really nice guy who says he loves me and I've felt a strong connection in the beginning, but now I just don't know what I feel. Meanwhile he's clear that he's in love with me, I debate with myself every day about how I feel and what I feel. And I feel bad and I feel guilty and I feel so exhausted from thinking. Because when I'm with him it's all good, but when I'm not it's as if I'm so far away from him, as if I'm alone again, as if I don't mind being away. And he's so good to me. If anyone felt this way or has any idea of what I should do, please don't hesitate to comment. Any comment is welcome and will be appreciated. Thank you.