You and Leon are partners.

*He gets jealous when you're with other men, but when he's with Ada, you can't ever say anything. It wasn't fair.

Leon always pays more attention to Ada than to you. One day when you were returning from a mission, hurt. Leon didn't even look at you, he instead went to Ada and asked if she was okay. Obviously she was, Leon risked his life for her, and she obviously didn't even care about him.

It wasn't fair.