In this situation, I think the man definitely needs his girl's support. He needs for her to help guide him in the right direction, give him advice not only as a lover but also as a friend, and to console, comfort and motivate him when things get rough.
I wouldn't even consider walking out. You were unsatisfied with him, and now, when he's trying to become the man that you want him to be, you leave???
I don't get it. This would be the time when he needs you most.
How many times have we all been faced with adversity and wanted to quit rather than persevere? And, how many times would we have quit if we didn't have the support of someone who loves us (mom, sibling, lover)? Finally, how many times have any of us quit because we gave up when it got tough? Would we have done the same if someone had really supported and believed in us during the tough time?