Cheating?

My husband and I have been married for almost 7 years now and we have a beautiful daughter. He has a friend that's a girl that has some issues (dad). My husband is a sweet guy and cares for people but him and her go out to see movies and are out for hours. I may just be being paranoid, he says there's nothing going on that they're just friends. Its very frustrating especially since he does a lot of things with her that he would do with me when we were dating. I don't know what to do