What is the date 11/22 about?

[dambolis89.livejournal.com]

edit: Solved! Thank you!

Okay, so I've been scratching my head to bruises and just wondering if you guys know what this is all about. When I'm looking at all the posts in Pixiv for Sweden and Finland, there are LOTS of pictures regarding a date 11/22 (November 22). I do have an translator add-on but I haven't found a understandable explanation. I also checked wikipedia for some historical events for this date regarding Sweden or Finland but I didn't really get anything.

Seems like some sort of anniversary themed since they are all lovey dovey. My guesses are:
1) It's an anniversary to some SwedenxFinland Himaruya's comic
2) It is based on some historical event
3) It's just date fangirls' have decided on together as Sweden's and Finland's ___ day. (if this is the reason I might just brake something)

I'm sorry for wasting everyone's time if this is a dumb question or I'm just digging way too hard on this. :D