When looking for flights to St Maarten the system picks what it thinks are the best flights and connections on either AF or KLM. Given the tight connections on offer at either hub it may be better to make seperate bookings and spend the night in Amsterdam on the outbound. I know the airlines are supposed to look after people who miss connections if on the same ticket but with only three flights a week or a re-route (probably minus your luggage) via Paris the next day your holiday is screwed.
On the return to the UK the system will pick the non stop AF over the KLM flight that calls at another island on the way back.