It's not quite that dire in Thai, but you're not far off base. It's your basic torch song, girl dumps boy, boy has no clue why. The feeling of the song is she is long gone, and he's moping because he wants to know what he did to deserve this.

What grabs me is he's using the phrase "praw arai". How to explain this to someone who doesn't speak Thai?

Oh, got it.

"praw" is like "cause". He's asking "what caused you to dump me?" Instead of "tom mai", "why did you dump me?" He wants a deeper answer, not something flippant or shallow.