Over Her Dead Body (2008)

Henry is a Los Angeles veterinarian whose fiancée Kate dies in an accident on the day they're to marry. Worried that Henry has closed off his social life, his sister suggests he use a psychic to contact Kate, lay to rest unresolved feelings, and live more fully. He tries it, though he doesn't believe in it. Nothing happens, so his sister gives Ashley, the psychic, Kate's diary. Now she's able to convince Henry she's in contact with Kate and start the therapy. Two things happen: they find themselves attracted to each other, and Kate's ghost, who also has some unresolved issues, returns to stop this budding romance.