Although I really wish I didn't have crazy to deal with - especially since it makes me feel like crazy might be why I like discipline and spanking, even though I'm certain it isn't - I've got more than my fair share. D. and I have been in together for almost 4 years and at the beginning I was much more sane. Take one traumatic accident (and the resultant stress about heights and loud noises) and sprinkle in a liberal assortment of mania and depression (and the perilous mood swings that come with them) and I'm more than either one of us can handle sometimes.
I'm sure it's why we've had more trouble with rules and why our dynamic has had moments of hanging on by a thread. We keep going, though, because we love this (and each other) and that's enough most of the time.