I got tired of reading through all of the redacted. Whether or not it is gender neutral or not, it is unimportant, I am going to answer the question as you asked it; that is why we are here, right?
When I worked in the nail salon I asked this very question of more than a few women, (when they discover you are not gay and you speak English, you’d be surprised how much they open up to you. You are almost like their barkeep). Those women who stuck with the cads and douchebags they were with (and complained about unceasingly), comes down to this:*
• With a bad boy thug they feel protected, should anyone bother them the bad boy thug would punch them or something.
• It was better to be in a busted relationship than no relationship, a condition made worse if all of their friends had a mate and they didn’t.
• It was always unpredictable, you never knew what was going to happen; it was like a roller coaster ride where you could not see where you were going.
• ”Nice guys” are too predictable and boring, they are not wild and spontaneous enough.
• ”Nice guys” won’t be able to protect them as much because they are not brawlers and street fighters.
• They (the females) felt that they had the right mojo to make him give up all those other girls and settle on her.
• They did not want to see all the time they had invested on the douche bag to go for not, so they had to stick it out in the hopes they could enact the above.
Out of 4+ years in the nail salon and conversations with dozens of dozens of women, those are the reasons women stick with bad boy cads, and douche bags.
*Many are sure to disagree, this is what I have gleaned, if you came up with something different after chatting with as many women as I, then go for it.