[W]ith partner abuse, the periods when the man is being good—or at least not at his worst—are not really outside of his pattern. They are generally an integral aspect of his abusiveness, woven into the fabric of his thinking and behavior.
What functions do the good periods play? They perform several, including the following:
- His spurts of kindness and generosity help him to feel good about himself. He can persuade himself that you are the one who is messed up, “because look at me, I’m a great guy.”
- You gradually feel warmer and more trusting toward him. The good periods are critical to hooking you back into the relationship, especially if he doesn’t have another way to keep you from leaving, such as financial control or the threat of taking the children.
- While you are feeling more trusting, you expose more of your true feelings about different issues in your life and you show him more caring, which creates vulnerability that he can use later to control you. […]
- He uses the good periods to shape his public image, making it harder for you to get people to believe that he’s abusive.
Lundy Bancroft in Why Does He Do That? Inside the Minds of Angry and Controlling Men (2002), pp. 150–51
"Good" periods also function to decrease a woman’s resolve to leave the abusive situation.