Girlfriend Infidelity

What is a good movie about infidelity?
I think my girlfriend is cheating on me so what really is a movie good they really make you feel bad if he has been unfaithful. or to confess / not cheating? indeed we have a baby of 16 months and have been together for three years.
"Unfaithful" starring Diane Lane and Richard Gere
Is My Girlfriend Cheating? Infidelity in Atlanta