
Is there a novel?

Yeah. Here you go in case you ask:
https://springofromance.com/chapter/rgs-volume-1-part-1/

Her revenge is... Giving him everything he ever wanted? What did she think she accomplished by making sure he won't grieve for a hundred years after his boyfriend dies by just making him fully human?? He was already known for being bored of everything in the ocean too cmon of ur gonna make a villain I want you to go all in this is like it Ursula made Ariel hydrophobic if she didn't kiss the prince in time, you're giving her exactly what she wants. Kinda disappointed in the ending but the side stories are cute

Hm, sure it’s everything he wanted but he also loved swimming in the sea. He may not have said it but Minu felt how devastated Yujin was. His love for Minu was just stronger than whatever feelings he had for the sea, and he got what he wanted in the end anyways. Eunha got the revenge she wanted as well, which was for Yujin to go through and understand heartbreak by cursing Minu. She also took away his life as a merman.
I really like this genre where the pet changes into a human bc it always starts out with a genuine platonic love to slow burn lifelong partners. If anyone has any recommendations like this I'd appreciate it! (Any kind yaoi, Yuri, or hetero). I'd recommend "Of all things, I became a crow" and "In the Doghouse"
I recommend
https://www.mangago.zone/read-manga/shouwaru_boukun_kishu_to_nagasare_senba/
I FUCKING LOVE ITTTTT 5 STARS IDCCCC
Just read that it was good but so short those two deserved 50 more chapters
I KNOW RIGHT ┗( T﹏T )┛ why are the good ones always so short!!!
seeing 'in the doghouse', i just know you have **great** taste, i'm following the recommendations ╮( ̄▽ ̄)╭
I actually meant "Don't Mess With the Puppy!" But my brain got confused with the titles lol no shapeshifting in that one, but it's still a gem
https://www.mangago.zone/home/mangalist/2928775/
I made a list for anyone following this thread feel free to add on to it