Why did my opponent give up?

He played a perfect game and gave up in the middle
I can not understand this ...

Maybe their doorbell rang?

maybe their cheese ball order from 6 months ago finally arrived?

I think he just had to go really fast. I've been in such situations and been doing similar stuff.

we was playing a tournamant, some seconds later he played the next game ...

Idk, my explanation is that he might've learned that he isn't required to go. But I really don't know.

I intentionally put the thread in the "game analysis" section
because I thought that some players would then evaluate the final position.

For my part, I saw no advantage on either side during the game ...

Maybe he realized he was playing a Crook (and lost interest). I know I would.

If the player returned a few minutes later, i'd assume he disconnected

maybe he thought f3 was winning the knight, but he missed that he had kf8

surely someone who was actually 2500 rapid would see human reason instead of just a computer evaluation