Is he telling me the truth?

How could you be sure that he is being honest with you. Even if it were true the fact that would he continue to upset you is not the remarks of a loving, caring partner. There could be an alt era motive in that he is insecure and thinks that by bragging to you leads you to believe that he is very popular hoping that you may feel that he is much sort after. Given that impression you may feel that you are indeed lucky to be his partner. You are casting judgement without any proof. If this continues I would rethink your partnership with him.