PTP, FDF, and CAY have flights and schedules geared towards France métropolitaine, as that's the main and most important destination (3 airlines too). Kind of like Hawaii and the mainland US. The flight from the DOM/TOM to the US has always been a cool afterthought, but an afterthought nonetheless.

A couple winters ago, AF tried a JFK - PTP link and one to YUL but the former must have failed to hit expectations because the following winter, they only kept the YUL - PTP direct flight on an A320.