There's another option here besides believing the full story or not believing it based on a lack of information. That's believing that it happened, but being able to acknowledge that we don't understand what happened. The details we know are enough to say Panarin did wrong, for sure.
I can immediately think of a dozen scenarios where Panarin misunderstands his relationship with the woman (on him) and then does something while drunk that he immediately regrets (again, on him). Plenty of variations on all of that too, and none of which blame the woman for any of it. None of it excuses him for what he did, either, but it's vital context if you're going to sit in judgment of him as a human being.