Should he stay or go?

My partner and I live together in the city that I am studying for my doctorate in. I have to stay here for another 3 years. He has recently been offered two promotions in his job. The money is the same for both, but one would help him progress in his career a little faster than the other. The one that would be better for his career is 5 hours drive from where we live, the other is 30 mins drive away, so we would still be able to live together. Money-wise, we could afford this. However, we would hardly ever see each other as we both have different days off in the week - so even if I went to see him at the weekend, he would spend most of it working, so I would be on my own in a city where I know nobody.
I have told him that I will support him whatever he decides and that everything will be ok with 'us' either way. Obviously I would love him to stay and be with me but not at the cost of his happiness and job satisfaction. He doesn't want to move away but then likes the idea of the far away job better. He wants us to make the decision together, but I think it should really be his decision alone as I cannot be objective about it.
What do you guys think? do you have any experience of distance relationships working/not working? should this be my decision as well?

We are in our late 20s and have been together for about 4 years