Boy Advice?

Theres this boy. We've been friends for a while but we've always been the flirty type of friends. He recently got out of a relationship with one of my friends. This friend now doesn't like me bc the boy and I are so close. He flirts many people but he's different to me. We've hung out a couple times and we're always together. I love him. But I just don't know what to do. I trust him but what if he's using me as a rebound? Or what if this is all in my head? I need help!