I agree that Bug stealing the car was definately bad, but that just shows he's not a perfect person. He was trying to be good or better for Lux, yet she was flirting with Jones, or at least that's how it came off to him. (PS. I'm a massive Bug fan, haha)
And, Lux didn't really support him. I'm not sure how I should explain this... umm.. okay, they've been together for a long time, they've experieced much of the same ordeals. And it's been tough for them. She isn't exactly perfect herself and sticking by Bug like she did was because he's always been there. He's been there for her and at that time she didn't really trust anyone else but her close friends from her childhood. So, obviously, she would stick up for him. Sorry, lame attempt at explaining that, I need coffee. Majorly.
I'm also a huge Ryan fan, goodness that man is just too perfect. I think it's the first time I've actually believed in a character like that. Usually, shows try an make characters so perfect that it comes off as being unrealistic. Somehow, Ryan just doesn't come off like that. woo!
I don't know if you watched the finale or not yet, but that Ryan and Lux scene near the end was brilliant! My heart just went out to him.