a fallback
A fallback chick is the girl who always takes you back even when you cheat on her. She’s the one who sticks around when you’re being a dog.
You cheated on her, and she took you back because she didn’t want to be alone.
You broke her heart, and she still took you back because she liked you.
You were a dog, but she still took you back because she didn’t want to lose you.