Since it's hard to rec based on what you like with so short a list, maybe Fushigi Yuugi, Ouran High School Host Club, or Chobits for romance? If you like love polygons and tangled romances, Nana might be worth a read for you. If you like love comedies + action, there's Rumiko Takahashi's stuff like InuYasha and Ranma 1/2. Those relationships blossom pretty slowly, though.
You seem to like Vampire Knight, and I've heard Black Bird is very like it. Haven't read that one, myself.
-And if you like weird and dark romances with strange taboos and corruption as a major theme, there's Kaori Yuki's stuff like Angel Sanctuary or the Cain Saga + Godchild.