Aside from a mother's love there is always God. :-)
The reality is anyone who is (mentally healthy) has a measure of "self-esteem" which entails having a line in the sand, boundaries, or "deal breakers" that will cause them to stop associating with toxic people in their life.
Whenever someone is unhappy or in an abusive relationship and they choose to stay, they are (choosing) to be unhappy. Having said that such people do exist who will be doormats, allow others to cheat on them, steal from them, beat them, sexually abuse them and their children....etc And they have NO plans to ever leave this person! They say things like; "I love him/her", "I don't believe in divorce" or "I made my bed".
However I must admit it is a small number of people that will go through all that drama without eventually walking away. Our divorce rate hovers around the 50% mark and women initiate 66% of divorce filings. Better career opportunities and higher pay for women has made a difference.
The more options one has the less crap they're willing to put up with!
Each of us chooses our own friends, lovers, and spouse. At the end of the day we are with whom we want to be with. The only person we can control is our self. Hoping for someone to change is a waste of time. People only change when (they) are unhappy with themselves.
In the eyes of God or a mother they can say: "I love you but I hate the things you do." However to the majority of the world "you are what you do".
If a person (loves them self) they will look out for their best interest and they will teach their children to do the same. Most people in abusive or unhappy relationships would never advise their children to follow in (their) footsteps! And yet they're setting an example for them.
"Never love anyone who treats you like you're ordinary."
- Oscar Wilde