Why do non-ADD/ADHD spouses stay in ADD/ADHD relationships?

I have visited this site many many times and have read so many of the posts and blogs on ADD/ADHD marriages.  I am in a marriage with a man that has ADHD and refuses treatment or even to recognize that he has it.  All of the problems in our marriage somehow are my fault, he has led us down a very precarious road financially, and I am the one who shoulders most of the responsibility in our family.  I am exhausted, angry, bitter, sad, lonely, etc., etc.  My childhood dreams of marriage and family are shattered.  With the exception of our two beautiful children that are a mix of my husband's creative, energetic side and my practical, sweet natured side I have nothing positive to say about our marriage of 6 years. 

My ever present question is, why do I stay?!?  Why do other people stay in non-ADD/ADHD and ADD/ADHD relationships where you never know what to expect, where you not only parent your children but parent your spouse, where you go to bed at night either feeling so completely exhausted from the day's roller coaster ride or you just feel so alone even when your partner might be lying right there beside of you.

I read all of these posts where people are so torn and so broken by the behaviors of their ADD/ADHD partner and while I gain solace from those posts, it also breaks my heart because I KNOW HOW DIFFICULT A LIFE THIS IS! 

Why do we stay????  And is there anyone out there that has really learned to not only just survive this situation but overcome it and thrive?!?