Answer
The answer is "Dan in Real Life", a 2007 American comedy-drama film directed by Peter Hedges. It stars Steve Martin as a widowed father of three daughters who finds himself falling in love with a woman (played by Juliette Binoche) who is staying at his bed and breakfast. Dianne Wiest, who played Steve Martin's wife in the 1989 film "Parenthood", also stars in "Dan in Real Life" as Martin's sister.