The look she gets in return for her question spells his guilt in a way he's hidden until now. There's only one thing he managed to do back there, and he's not even sure exactly how it happened beyond a few crucial errors. His intentions started out so differently.

"On the ship... I tried." Which is a gentle way of saying he didn't succeed. As shaken as she is now, he's beginning to choose his words more carefully. "...After that, I had to go away for a while."