Okay, as Nephy said, trust is very important in a relationship. In fact, with the level of doubt you have now (wanting to hire a p.i.) it will be very hard for the relationship (to return to normal and) continue even if you find out that he's not cheating. You're crossed a certain street that has taken you a step away from the relationship.First, I'd say to confront him. It's more direct. But then I'd say, don't confront him. Go sneaky and follow him around a little. Asking him of his whereabouts can send the wrong message (or this time the right one) that you're suspecting him. Which is a breach of trust if it turns out that he's not having an affair;).