Jumping for her
He would have jumped out the line for anyone, those people were his family after all. But he jumped for her. The adrenaline wore out fast, his rebellion was short-lived, but he didn't care, he got what he wanted. It was his life in exchange of hers, and he thought it was a good deal, he should have died a long time ago instead of Merlé, instead of Beth, instead of so many people. But for some stupid reason he was still standing and somebody else wasn't. He thought "not this time"... and he was wrong.
She was frozen, looking at the ground, crying quietly with her mouth open and her breath broken. But she was alive and Glenn wasn't.
He would have jumped out the line for anyone, but he did it for her in exchange of his own life. Nobody told him that the price to pay wouldn't be the agreed price. He should have known, people like Negan never respect the rules, people like Negan make the rules a changing game dependent on their whims and their moods. He should have known because his family were like that, and his childhood was a cruel game that he never couldn't win
He left the clear as slave, grunting and fighting like an animal, and he would keep fighting until his last breath. Once he was left alone in the dark he thought, and dreamed and wondered... He would have jumped out the line up for anyone, but he did it for her... and he didn't know why