This woman isn't in love. She has an unhealthy attachment or what the experts call trauma bond.
People with trauma will accept toxic situationships because they have a fear of abandonment. They also start to reason that even though they're not getting the relationship they want, something is better than nothing, and the other person still provides some benefits.
A man detested his wife. She was a difficult and critical person who lacked any affection. However, she was a very industrious person who knew how to build wealth. She was also a good mother to their children and was very efficient at managing the household. Plus, she wasn't the cheating type.
The man did not divorce the wife, but cheated on her instead, to soothe himself. He kept a side chick throughout their marriage. The other woman was barren. She was soft, agreeable, and attractive. She was also industrious and could manage the house. However, the man never married her. Not even as a second wife. He just used her to cope with the dysfunction at home. Perhaps if the man hadn't already been married, he would've liked to marry the mistress. But he felt overwhelmed at the thought of going through a messy divorce, splitting up the kids, losing assets, fracturing the family even more, and above all else, bringing the mistress he loved into the drama.
Therefore, the man continued to avoid being with his wife and instead, stayed busy working overtime then sleeping at the mistress's house.
The man continued to live this way until one day he killed himself.
So you see, the wife could've also left the husband. She knew full well that he hated her. At the same time, she couldn't stand him either. She felt very irritated by the way he talked, his hygiene, his humor, etc. But she did not divorce him because they already had a family.
There are many people who stay together because they're used to being miserable together.