I saw this movie about 10 years ago and I think that it was on the IFC channel. Only things I remember is that there was a family…mom and dad and two daughters. They had a house on the beach and the parents liked to have parties. The younger daughter always following big sister everywhere. Movie was set in the late 60s or early 70s. I believe they had British or London accents. The mom and dad didn’t pay much attention to daughters…too busy smoking pot and partying. Older sister gets tired of younger sister tagging along. Older sister has a crush on a guy and decides to go make out with him and leaves younger sister on beach. Younger sister drowns and dies (I think she dies)?while big sis is off making out and parents are having a party . That’s all I remember! Thank you for any help you can provide!