Oh, man, haha. My most recent ex specifically:
Conflict-avoidant. He didn't want to "rock the boat" and wanted me not to, either, even when one of his friends would make nasty comments.
Rarely kept his word about the small things. Best example: Early on, I introduced him to my favorite show. We promised to watch the season finale together the next night. He watched it on his own while I was at work.
Rarely kept his word about the big things. Best example: He promised he'd say something about the above situation with his friends with me. He didn't.
Hated his life. Never did anything to change it. Work, video games, sleep. I tried to nudge him back into music (he used to play trumpet/bass) or exercise.
Biting my tongue on a few things I can't word politely, so I'll stop there. I stayed with him longer than I should have because deep down, I don't think I felt I deserved any better. Dating him was comfortable and easy, and he was "nice". I was very unhappy with myself, but eventually outgrew that and moved on.