Please help me!

So my fiancé is working as a technician and its wearing him down. He is constantly working, even at home and on his days off. It's causing so much stress on him and our relationship. He's not happy. But with all that said his job is his career job and he makes a good amount of money. He's contemplating on whether he should quit and go back to his old job, where he actually had time for himself and his family. Where we had less problems and we were happy, but had less money. So I guess me question is, what would you do? Choose being happy with less money and give up a career job or stick with the job and just suck it up because its better money?