If you are in a relationship and stay at his house frequently, I think it's a reasonable thing to ask of you. He is concerned and he trusts you...it's not like you are going to some random friend's house or something... He hasn't asked you to confront anyone or deal with the issue so I would do as the previous poster said. Check in and report back what you find...although the deed is done at this point or not done, I'm guessing based on the time.