Well IMHO based on the facts, and without discussing the law at all, it sure looks to me like somebody is going to be unjustly enriched, no matter what.
I'm gonna assume that there's a good chance that if the entire final two weeks of the 2016 presidential campaign were focused on Stormy Daniels and her story about screwing one of the candidates who was cheating on his wife shortly after his wife delivered a baby son to the candidate, instead of the final two weeks being devoted to the other candidate's emails that were found on a laptop belonging to a guy who liked to show pictures of his penis to young ladies, it might have been enough to make the outcome of the election different from what actually happened. In short, Trump might have lost if my gal Stormy had run around flappin' her gums on the Tee Vee those last two weeks.
And as we all know, Trump has been looting the US Treasury since the day he took office, to the tune of a hell of a lot more than $130,000. As between the lying bastard sociopathic crook and the lady who gets paid to take off her clothes, I'd say that even if she gets to keep every nickel, he was WAY WAY WAY more unjustly enriched than she will be.
And as we also know, Cohen was already more than compensated for the money. He got repaid more than $130,000. And unless he plans to return anything he gets from Stormy to Trump - and fat chance of that, given the current situation between the bad lawyer and the bad client - if she repays $130,000 to Cohen, then he will be unjustly enriched in that amount, free and clear.
And I have a very strong opinion, assuming one of these three people will be unjustly enriched, which one it should be. One of them got nekkid with the disgusting greasy old crook. There isn't enough unjust enrichment in the world to make her whole.
But that's not legal analysis. I'm just snarkin' and barkin'.