I know a lot of people are blaming Geet but I would like to point some stuff out.
Firstly some people asked where her self-respect was one she forgave Dev and how come it comes only with Maan. The simple reason is that she cares for him. If you don't like someone than you don't really care for their opinion.
Do I think she should have left the house? No. But I can understand why she did. After this comment she would always have doubts that he thinks she is inferior because of his "Khurana" blood. (I know he doesn't think so!). In a relationship respecting the partner is ESSENTIAL, otherwise there is an imbalance. Not that I think Maan doesn't respect Geet, of course he does. But if someone says that to you, would you not wonder what they really think of you? Just like Maan got carried away by the moment so did Geet.