Is there a shadchan? Can you speak to him/her?
That must have been a really upsetting experience! I have never experienced anything like it,but I am sure I would be heartbroken! Even to the extent that I have ever experienced such a thing on a much, much smaller scale, I was heartbroken.
I am not sure you will ever get a real answer. It sounds like there is a good chance that this has more to do with him than with you (which is
why you may never find out the reason).
If so, Hashem may have just spared you from a catastrophe. Of course, it’s probably hard to be happy about it right now.
Im Yirtzeh Hashem, you should be zoche to find someone much, much better!