"This was the hardest part about a marriage, or a relationship like theirs: your hopes and your fears and your happiness hinged on someone else." This quote highlights how deeply intertwined emotions and expectations are in a close relationship, making individuals vulnerable to the actions and feelings of their partner. It emphasizes the delicate balance of giving and receiving love, and how dependent personal well-being can become on another person.

"When you stopped thinking that they ought to, you ended up like her parents, bitter and angry and apart." This part suggests that letting go of unrealistic expectations can lead to bitterness and disconnection. It underscores the importance of managing hopes realistically to maintain harmony, or risk ending up resentful and distant, like the example provided. The quote portrays the emotional consequences of both clinging to and relinquishing expectations in relationships.