Name of french comedy period film where people fly away at the end

I saw this film a few years back on ARTE. It was a French film but dubbed in German, I can’t remember any of the actors or the title.
It was set in the 19th c and in it this posh French family goes on holiday to their country house. One of the children, a boy, is always dressed up as a girl and he falls in love with some fisher’s son.
At the very end of the film some of the people suddenly start flying… that’s all I can remember.
I know it sounds like a fever dream but I definitely saw it and remember looking it up as well, only now I can’t find it… please help!!!!