She learns for him, will not leave him
So much speculation and it's been going on for years that she will finally leave him because he won't, ever, change. But do you know the lengths she went through to get him, and keep him? Did you know she enrolled in classes at university, not because she was interested for herself, but because she wanted to be able to talk to him about...things? She wanted to be able to keep up. She wanted HIM to know/believe/think she could keep up. She worships his brain. She wanted to make sure that he was finding her brain adequately stimulating.
They say that he's been trying to get out of there. He hasn't tried. There has been no attempt. It's kinda futile. First because, even if he were to want to bail, everyone in his life would be against it, and has warned him of the consequences, but also because she has told him straight up, on several occasions, "I will never leave you". This one doesn't get enough credit for her tenacity.
Top suspect: Jennifer Garner and Ben Affleck (revealed at smut soiree)