As all who have written here say, every woman and every relationship is different. It's also true that women are very unpredictable and changeable - at the risk of being shouted down by feminists, I would say that women are more-so than men in my experience.
But what I do know is that you must never be too afraid to walk away. Of course it is horrible and you will feel wretched without the person you have invested so much time, emotion and money in.
The upside of having the ability to walk is that there is gold in them there hills. If you can find the strength to do it once, you can do it twice...three times etc. And you'll know you
will get over it...you really will.
So you will never again be held hostage to changeable emotions and moral blackmail. You don't have to be nasty or aggressive about it but you will be able to stand up for your needs, express your feelings from a position of strength and address problems as they arise - free from risk.
My ex-fiancée ended our relationship two years ago now. She was on about the third personality by then! She did try to re-establish the relationship a couple of months after dumping me. I could have gone back but I said a very firm
no! - first to myself and then to her. Things will never be right so it's not worth pursuing. Of course it hurt but I had to go and I don't regret it.
I've had a couple of dalliances since but am now single - but I'm in control and it is just fine by me.
I hope you can find a way forward but, as I say, never lose sight of the option of walking away.
