Seems kind of cookie cutter.
Also the whole she lost her engagement and her family disowns her is insane. Is this a Japan thing?
If you look at how things happen in the west, if a man or woman decides to legally marry a commoner their family will disown, king Edward and Mrs Simpson is the perfect example. where he even lost the crown. Prince William is another good example. Unless the person marrying down has solid control of the family, it will be a problem
Being engaged to the king is rarely a negative
At least this one realizes Saint x Sex = no no no, burn witch burn
P.S. Wallis Simpson was a real life heroine with a MC halo that destroyed life for everyone around her. There's a couple of good movies of the 'love story' and some decent articles on the real life aftermath