Some people dont know what to do in an abusive relationship and they keep fighting and begging for the relationship even they are treated really terribly by their partner.
especially, Im assuming she/he moved from a foreign country to move to be with his/her spouse which means he or she probably doesnt have many connections here in the states and probably highly dependent on the USC partner,
Moving to a different country for someone is a big deal, its not a joke, so much sacrifice, efforts, leaving family behind. and people feel that they dont want to throw it away easily.
I understand it very well, marriage is a big deal as well. Marriage is making a vow to be with that person forever.
people in abusive relationship believe their partner can change and their relationship improves even the abuse continues, too sadly..
Also, I believe there is a category for people whose (Petitioner or USC)Spouses are refusing to file jointly I-751