I think both House and Wilson were terrified of the fact they loved each other, because they weren't who they wanted to love. Wilson wanted to love a nice, successful, intelligent woman. House wanted to love an attractive woman. So, I think that they tried to deny that fact, until it came out that Wilson was dying and suddenly their forever together was very short. Hugh Laurie said something about the final arc being when they had to just say what they felt about each other, and what did they say? "I need you, okay, because I don't know what I'm going to do without you," "I don't want to loose this time with you," "I need you to tell me that you love me," etc. They were the loves of each other's lives no matter how much they tried to fight it.