I've been playing with the idea of putting Persuasion into a Faerie setting. And one of the first things I was looking at changing the serial numbers for was the original breakup.
Now, there's a lot of reasons why they might break up. A quarrel, stupid or otherwise. A mischievous illusion that separates them misleadingly. A kindly Admiral telling her that it was not good for his career, marrying a land fae. Complications because she's a fae and he's a selkie.
But all of them change the flavor of the breakup somewhat, or a great deal. Sometimes you just need to steal it all.