Firstly, I hope you don't think I'm being patronising, but really well done. So many people stick around even if they see the early signs mainly because of fear of loneliness or lack of self worth. Self worth is taught to us mainly by our caregivers (parents, adopted parents, foster parents, ...etc.), to a lesser extent by our environment. The reason why women, and men, accept being physically or mentally bullied by their partners is because most of us witness parents who were not in love. In other words, they were ok with living with someone that they knew did not love, respect, or admire them. They may have got on with it and did their jobs as parents as best they could, but that is not love, that is being a work colleague. Demonstrating to children that its ok to live with someone who's company you don't enjoy is how low self worth is taught. If I see my mum or dad smiling and being happy with friends, but then the minute these friends leave and my parents are left alone, the smiles go, the mood changes and it becomes a functional thing, then I will learn that its ok to be at home physically, but mentally I wish I was somewhere else. This is a very dangerous thing to learn, this is what leads to accepting mental or physical bullying and violence.
Therefore never accept, never suffer in silence and more importantly, if you suspect that a friend or loved one may be suffering, get to the bottom of it. Do it not just for your sake or your friend's sake, do it for the children's sake. We need to break this cycle of tolerating lovelessness so our future kids have far more self worth and domestic violence becomes a thing of the past.