A lot of people stay in unhealthy relationships because they have developed a belief that they can’t get another mate. They believe that being with someone is better than being alone, even if that someone mistreats them and adds nothing of value to their lives.
Back in the days of our great grandparents, couples generally tended to stay together. The morals, customs and religious beliefs of their era kept marriages intact. Many women feared having children out of wedlock, causing a scandal, or of being an old maid. Most were uneducated and unemployed, remaining at home to take care of the family. They did not have their own financial resources and quite literally didn’t have any other option. From a cultural and religious perspective when you made your choice of mate, you were stuck with it, whether or not it was a good one.