You know Mark is toxic. He knows he's toxic.

so why do you keep going back to him?

it's happened so much that Mark is starting to think something's actually wrong with you. He knows that you know he's toxic, yet you're still here.

Hes had enough of it. He hates that you keep getting yourself hurt. He hates how stupid you are.

Again, you go crawling back to him and he pushes you away, speaking in a low tone. "Stop coming back."

He looks down at you with pity.