Lucas: I still don’t understand why you wouldn’t let me retaliate, though. They stole your dream.
Cuddy: Well, that’s overstating it. It’s just a condo.
Lucas: It’s not because you feel guilty about hurting House or guilty for being with me?
Cuddy: We’ll buy another one. I just don’t see the need to make a war out of it.
Lucas: Well, I think you’re rationalizing, which a less confident man than myself might take as a sign that you’re second-guessing…Okay, you know what? Forget that last part.
I thinks this is a cruel scene. Lucas is trying (in his own way) to asks Cuddy if she’s having second thoughts about their relationship, then she kisses him to reassure him. At the time it was a misleading by the writers to make you think Cuddy really was going on that direction, but by the end of the season Cuddy tells House “I always love you” so here, she’s leading Lucas on, and for me that’s plain cruel.