John: "Gaby, I'm sorry to disturb you, but we're ready to cut the cake."
Gaby : "When Justine took her first crap on the potty, I wasn't there. When she had her first sexual intercourse, I wasn't there. So give me a break, please, with all your fucking rituals."
John is very much the keeper of family ritual and in many ways, the keeper of normalcy, wanting to pay heed to the things that are supposed to be done - the things we do because people do them. He does not want Justine to cut her cake before Gaby is present. Gaby, on the other hand, sees a bitter irony in this; she wasn't there for so many of Justine's pivotal moments, the marks she was meant to hit in her life, the milestones, and so to her, worrying about waiting until she is present before cutting a cake is an absolutely ridiculous concept. She does not want to participate in rituals that she feels are for the benefit of how things look to other people when she knows that to her, they are false and hollow.
I'm happy that you're happy.
Justine is not a happy person. She tries, and she wants very much to be a happy person, but she just isn't. The only happiness she feels is for other people. Claire is happy, and this in turn makes Justine happy, in a way that her own feelings and reactions to the world around her never can. She also seems to feel more able to control her happiness when it is for other people.
