OP, I actually have another theory. Some of us picky women don't like to get or send both Christmas wishes and HNY wishes in close succession. Mindful that not everyone celebrates Christmas, I only send one short message with seasonal greetings around New Year's. Wishing her Merry Xmas and HNY might have made her a bit uncomfortable. Just a theory, I'm curious what other people think.
About getting rejected, well we all do. I used to be really good friends with a woman at work, share women's stuff, and then I saw on fb that she had gotten married. I was a bit shocked not to have been invited, but I liked her pics and wished her happiness etc. She unfriended me immediately and never spoke to me again. After a while she moved. Years after I found out that she had cheated on her soon-to-be hubby with a work colleague that I was also good friends with. So I guess she was in some self-protection mode.
Anyhow don't beat yourself up over this.
For the others: About him really having good memory, I think it has more to do with the game than some obsession with this woman. He's more upset at being rejected, we can assume he's fairly young.