CONFUSED! Wondering why. Wishing I could find out and maybe fix it. And then, later, nothing. The feelings go away.

My best friend from youth cut me off over a decade ago. I had brief contact with her years later and she said "oh you did nothing!" but still wouldn't talk to me. 

Years after that she wished me a random, overly friendly happy birthday on facebook. It confused me, but I harbor no need to reconnect anymore.

tldr - confused and then I got over it.

THIS. I know that it's not always true, but it's true a good chunk of the time!