The Thistle in the Kiss (1970)

Declan has had no luck with the holidays: his girlfriend Stephanie broke up with him on the way to Christmas dinner. He's managed to keep it secret until New Year's Day, when his car breaks down and his sister Rachel shows up to help him fix it. Crumbling under her relentless curiosity, Declan is now on a crash course to confront the poor decisions of his life.