Why is this guy pretending to everyone we had ?

Exactly the same thing happened to a friend of mine last week. A rumour started that his wife had come home and found him in bed with another man. He was most upset and started trying to find out who started the rumour. He protested to me that it was untrue. So I gave him the advice I'm going to give you. Ignore it and it will soon be history. He took my advice and within a couple of days it had fizzled. The worst thing you can do is feed a rumour.