Maybe almost a decade ago — 2016 or 2017? — flying from Tokyo to LAX on UA, I was moved away from a drunk man who was repeatedly harassing me with lewd comments, kept trying to touch me etc. When I brought it up discreetly to a flight attendant when the guy was in the bathroom, they moved me immediately to an empty row in economy plus. This was about 1/3 of the way through the flight. I was a female in my 20s (with a bit of a baby face at the time) traveling solo, so that might have made it more urgent for them.