Responses
It's because he has supposedly a lot part time jobs plus being a student. It wasn't clear if he actually quit the BBQ place but if he didn't, he'd have 2 jobs plus school. In the end, she supports him with the exam. That means, if he pursued being a trainer after graduating, then she's supporting it.
I came back and finished reading it, since I stopped 10 chapters from the end. It sucks, but not because she slept with the blonde, she's extremely controlling. The ML wants to be a PE teacher and you can see he really enjoys helping people train, so when an awesome opportunity came she made him decline it? WTF? And with the excuse that they'll see each other less? Is not about the money is about doing what you like, why can she have a career and he doesn't? That's not love. I really hated that, awful ending.