Is this a sequel to "Fall" ?

I suppose so. I've seen both films and Eric Shaeffer plays the same character - writer Michael Shiver. He even mentions in After Fall, Winter (2011) his affair with Sarah (he tells his friend that he hadn't been to Paris since he broke up with Sarah). Also, according to Wikipedia:

Fall is a 1997 film directed by, written by and starring Eric Schaeffer, alongside Amanda de Cadenet. The film was followed by a 2011 sequel After Fall, Winter.