I am much more optimistic about marriage and medical school. I have found that being married provides foundation, stability, comfort, joy and support that my umarried friends don't get.
And being married to a medical student won't screw up your financial aid. You will each be able to say that there are 2/2 people in your household who are in school FT, which is treated the same way by FAOs as 1/1. And if you are maintaining separate houses, you will actually fare better.
An hour and a half apart isn't bad at all. You could live together somewhere in between, you could have two places and during periods where one person has a light schedule that person could stay at the other one's home, or you could turn each weekend into a honeymoon.
My husband and I lived in separate countries for the first year of our marriage, and although that was unbelievably hard, it was also wonderful. Every time I saw him I was in heaven.
If you are ready to get married, do it. If you are not, don't. That should be the biggest determinant. If you are young (under 30) I recommend holding off. There is a lot of personal development that you go through in your 20s that affects the success of a marriage ... and if it's right, it will last that long. If it's wrong, it's much easier to break up than to divorce.
So the advice I give has nothing to do with medical school, but instead with your age, your relationship, and your readiness to commit to a lifetime with one person.
Capri