How Not to Live Your Life (2008)

Don is a single twentysomething who constantly fails to guide his way through life. His overactive mind doesn't help things as it plays out scenes of what he shouldn't say or do. When he moves into his recently deceased grandmother's house, he meets Eddie: his Gran's carer who doesn't want to leave. To help pay his rent, he decides to get a roommate in the shape of his teenage sweetheart...