| Quote #1
Then he leaned forward and whispered into the ear of the woman in the green dress. She was still for a moment and then threw her head back and laughed. (1921.18)
After leaving Eva with three kids and no money, BoyBoy returns, accompanied by a woman who seems to be his girlfriend. After a short visit, during which he fails to even ask about his children, BoyBoy walks out and says something to the woman that is probably about Eva. When the two laugh, his betrayal of Eva is complete. Not only has he left her; he's now making fun of her with another woman.
| Quote #2
Hannah simply refused to live without the attentions of a man, and after Rekus' death had a steady sequence of lovers, mostly the husbands of her friends and neighbors. (1921.39)
This is betrayal in the most common sense of the word. Hannah betrays her friends by sleeping with their husbands, and husbands betray their wives by having affairs. This type of betrayal becomes quite significant later in the novel.
| Quote #3
Sure you do. You love her, like I love Sula. I just don't like her. That's the difference. (1922.33)
Hannah completely betrays Sula here. She isn't careful enough to make sure that Sula can't hear this conversation, and her words devastate her daughter. Is Hannah required to like her daughter? Perhaps not, but the betrayal occurs when she voices these feelings to her friends.