This is what jumped out at me in your post. I hope you will believe me and trust me when I say that there is NOTHING that YOU can do to change his behaviour. He is displaying classic borderline and abusive behaviour (the splitting, the constant back and forth, the manipulation, the excuses, the constant crises, fear of abandonment, and so much more). This behaviour will NOT change until and unless he decides he wants to seek help and make changes in his life.

The others have already asked some good questions. At the end of the day, what can you live with? Can you live with this kind of stress, tension, uncertainty, manipulation, and anxiety? Is your life worth more than this? What do you owe him that keeps you coming back? Would you be happier in a healthy relationship? Do you need to settle?

Only you can decide what is best, but living with a borderline is NOT easy or fun. We are intense, constantly in crisis, constantly putting out fires, constantly creating crisis, and high maintenance. I know I wouldn't date me.