Catch 'em going or coming back, it doesn't matter. The couple that thinks they can save the relationship with the perfect trip will only piss all over your pleasant jaunt.
If they're flying to sadness, you'll notice they're gritting their teeth, like they're both due for simultaneous enemas, or something else just as nice. The way they start sentences only to give up midway, as if the situation's so fragile that the wrong turn of phrase could fuck it all, even before they get to Sandals, that's a tell, too. They're holding hands because that small act of human kindness and the dimming prospect of hotel sex (maybe with eye contact?) is all they have before the inevitable.
And when the inevitable comes to pass, you'll find that they're not even starting sentences. They aren't touching. They don't look at each other. Sandals was a trap. The last chance was no chance at all.