It's understandable if you want an explanation for this behavior. Being left out in the dark is not an easy situation to be in especially if you are confident that you haven't done anything wrong.
However, there's really nothing you can do about it if the person wants space from you. No matter how much we want to seek answers for our questions, we have to accept that we can't get it all the time.
Do yourself a favor, move on, and realize that for every person you lose there could be more to gain, and you should take what you learned from this one and use this insight to improve them.
The situation that you're in is a test of how mature and understanding you can be. And I hope that you pass and learn from this one.