It's really not that uncommon. IIRC the main couple in Love Sick's actors were 17 & 20 when it first began airing.
Cultural sensibilities can vary. It doesn't seem that the Thai have much of a problem with it. I remember when a fuss was made by some about Ohm Pawat being only 16 and Toey Sittiwat being 20 when they starred in Make It Right. They were the best part of that show. Who cares how old they were?
NOTE: The movie is English subbed but the Trailer isn't (for some reason).
https://youtu.be/UDilz1RRr6I
https://kisskh.at/30443-holy-fox-son-1-advent
If you like the theme song, here's where it's from:
Title: Double Love
Artist: ICE Feat. NamCha
Year: 2012
https://youtu.be/uDsatUx4Cv0
GMMTV is posting this now on its YouTube channel. Yay!
https://youtu.be/vY3OAI1Bj0A
Loved watching Tay and New!
https://youtu.be/GpCISrfuomQ
After that, the two come to some sort of understanding and Bai Luo Yin realizes that he does, in fact, have deep feelings for Gu Hai.
https://crescentmoon.blog/dark-blue-and-moonlight/
Ep 2. Bi = Cheating. Ugh. Not again.