The eternal question.
I recently flew on a ridiculously low fare for a holiday, and was stuck in Y for 3+ hours, which was fine for what I paid. Twenty minutes after takeoff, the man in front of me reclined, essentially forcing me to do the same. I checked the gentleman behind me, and he was asleep, so I gently reclined without waking him.
Half an hour later he awoke and began repeatedly kneeing my seat back., which I ignored. He, of course, had been reclined the whole time.
I ran into him on the train on the way back to the city, and he regaled me with his sob story about the person in front of him who had so rudely reclined without asking.
He didn't recognize me, but his wife did, and she blushed quite floridly.
We are all in this together, so we must just get along.