Proof of Cloud's feelings after Aerith's death, but during the events of the game (and the only point in Cloud's life where he and Aerith knew each other) the evidence is not so plentiful. I say that he did love Aerith during the course of the game, but people move on and I think he fell in love with Tifa afterwards.

Sure, some of you have put forth evidence for Tifa, and maybe you're right. Maybe it's just I'm a little biased because I really liked Aerith and the idea of her and Cloud being together. But so far, I have not seen anything definitive in-game that would prove who Cloud loved.