We covered all of our "deal breakers" when we were still in the LDR stages, because then we'd be able to cut our losses, so to speak.
1. To have/not to have children. We chose "not", for many, many reasons which make sense for our life and life style.
2. Lying/cheating-We said that we'd rather know if the other person has gone off us, point blank, rather than lying/cheating to each other. Besides, I'm an awful liar, and it would do my head in, spinning all sorts of stories!
Those are about it. I married my best friend, so I know the good and not so good, and vice versa.