Someone who describes a social interaction to me which made them sad or angry or bewildered and then asks me to explain why the other person did whatever it was that they did.
Now, I’ve been acculturated to enjoy the hobby of armchair psychology as much as your next Child of the 60s, but I’m so over it, because it’s ultimately so pointless when discussing real, actual, lives (as a hobby with characters in entertainment productions? sure, bring it on – because the writers have scattered many clues, so it really is a puzzle to be solved).
If you want to know why somebody rebuffed or rejected you, or whatever it was that they did, then why not ask them?
Sure, you might feel nervous about asking them in case it makes things worse. That’s understandable, although it might mean that you ultimately have to accept that you will never know. But in this case, what good does it do to ask somebody else their opinion of an interaction which they did not observe, let alone take part in?
Of course I (and most other people) would be able to speculate as to dozens of possible explanations, some that cast the other person as having a good reason, some that cast them as having no good reason, some that postulate a misunderstanding, some that postulate you inadvertently triggering painful memories, some that wonder whether it was just a bad day of sensory overload for the other person etc etc yada yada yada badabing badaboom and all sorts of shades of grey in between.
But in the end, especially if I don’t know the other person and am only getting your side of the story, it’s all just partly-informed speculation that lacks any genuine insight, no matter how much of what wisdom I’ve acquired over the years I might strive to harness for the purpose. Because none of us know exactly what is going on in someone else’s mind, or what experiences from their past have influenced those thoughts and their behaviour.
People are not puzzles to be solved, and treating them as such does not lead to good worldviews.
Addendum: this is why I appreciate good advice writers like those at Captain Awkward so much. The advice focusses on why the person asking for advice is feeling sad/angry/bewildered, and how they can use their words to stand up for themselves and negotiate better interactions (or avoid the worst ones), not so much on why exactly the other person is doing what they’re doing (there’s inevitably a temptation to speculate somewhat, but it’s not the major focus of the advice given – certainly not any idea that the other person(s) can be ‘fixed’ somehow if only their puzzle can be solved).