I've come to appreciate this story recently. It's because I heard the full story of the Snow Queen where the Snow Queen wasn't a bad guy, just a fairy that took Kai. The mirror shard that went in his eyes weren't even the queen's doing, it was supposed to be shards of a mirror from hell that made its victims see the worst in people. That's why Kai went with the queen of his own accord, since under the spell where he hated everything with imperfections, he loved the beautiful Snow Queen. The conflict towards the end is more about child neglect since the queen didn't take care of Kai and almost let him freeze to death.
It seems like this manga took the attitudes of the Snow Queen and Kai and put them into this story. The queen still doesn't know how to raise children and Kai still is fascinated with the Snow Queen. It seems like the author's main change was creating a romantic relationship between the two - which would always cause problems because of the age gap. Idk. It's interesting to me how the author interpreted the tale and decided to incorporate it into this romance story. Or should I say incorporate an alternative romance in the Snow Queen? Either way, I don't really have a problem with it so far. I'm not sure if the queen actually is a mother like figure to Tita or if he's always liked her - similarly to the way Kai did. I more appreciate the story telling rather than real life application.