I don't know much about the real folk story told by Thai people, personally I love Thailand but if this is it then Apai Manee did do well, it was hard but he had to.
I mean he was a really good brother but he was also an okay father escaped with his son as well as the mermaid's family.
But then even if he didn't love the sea ogre he should not have cheated on her and included his son also because you could see clearly that she really loved him.
Whiles his humbly and loyal brother searched everywhere for him he was busily falling in love, when his brother was so depressed over him. He had no choice but to make a baby with the sea ogre.
I think she would have not had such a fate if she had not been so jealous.
I still don't understand why Apai Manee left his son with his brother to go with the mermaid. And also his son is such a brave boy. A must watch definitely worth the time