Yup, I can sympathise with him. Something similar, albeit with a shorter-term relationship, happened to me last year. My girlfriend at the time, Karen, was quite supportive and I thought she understood and accepted that I worked a lot. After three weeks of working inside radio towers and a couple of weeks being very very ill she left me.
She told me afterwards that she was dropping all kinds of hints which I obviously didn't pick up on. I think she associated "getting hints" with "paying attention" and "caring".
I've now realised that, at least for now, I had to make a choice between a love and a passion. I know a lot of you out there will hmph!, citing that there are plenty of examples of people who keep up active passions and a healthy relationship.
I'll simply note that I am not them. Oh, and I have too much on my plate already.