Pairing them up is fine. Pairing them up by having them first meet because she's being manipulated by Noah to manipulate Sylar into becoming the ultimate evil manipulator...wacky! Honestly, I don't remember much about their romance. Just how they met, that she's the one who taught him that he can steal powers without cutting people open, that they got it on during the eclipse, and that he killed her 'cause suddenly it was time for him to be all-out evil again.