I think that the 'never' is a safety mechanism for him. He probably does mean it because he feels that it is the only way to protect himself from a destructive relationship.
When I suggested that you ask him that question, it was only because you seemed so sure that the two of you were destined to get back together.
Also, I wasn't suggesting that he would answer or agree, just that, if you were determined to try, that this might be something that you could put to him ~ without pressure of any reply.
If you do change ~ then maybe he will change, too.
You cannot expect this, but it might just be a possibility.
And, as he says, if you do change, it will benefit future relationships for you ~ with him or with someone else.
But do look inside yourself, at what is going on and why.
You are bound to feel sad and lonely and confused and rejected right now, so look after yourself and try to get involved in positive interests.
Perhaps you could spend some quality time with friends or family. Have you asked them for unbiased opinions on you and your relationship?
Good luck!
