That's funny my husband will sometimes ask the same thing. Even through the pain there are plenty of good reasons. I can separate out the good from the bad and love him for things in the past and good and admirable things that I know are inside him.
I have a close friend who was pretty happily married for 26 years and when her husband went into MLC and the whole senario she couldn't seem to get over him "doing this to her." Regardless of what I'd say she'd hold onto her anger and bitterness. Her divorce will probably be final this month. For a long time I would try to calm her down and explain... yes, what he's doing now is painful and wrong and I can't blame you for feeling hurt and angry, but on the other hand... this is a guy who gave you 2 great kids, 26 years of a fairly good marriage, you're getting half his house and alimony. What about appreciating that!!!! What about wanting someone who gave you so much to be happy regardless of where that might be (I basically was trying to convince her to DB, but she did everything opposite of what I told her even through she did tell me everything I told her made logical sense ).
There is no arriving, ever. It is all a continual becoming.