I don't think you can go for the harem route. It's hard enough to balance all the things you have to do in-game with the limited time. But I might be wrong.
IIRC you have to see him 5 times. How many times have you went to visit him?
Anyone who's played the game want to share their favorite romance route for each of the Hosts? I think I wanna try Jon's first for Katy, and Eric's first for Jon, when I get to play the game. :)