The former England and Manchester United striker, 35, married Kristina MacMillan, 29, last June in a glitzy ceremony at a castle in Cheshire.
But they split in November after she reportedly caught him in an affair with married Sarah Cox after fitting his car with a tracking device and following him to a spa where she caught them kissing.
Alan Smith, 35, split with his wife Kristina MacMillan, 29, last November, according to friends
Now his relationship with Mrs Cox is also said to have ended - 'almost immediately' after his split with MacMillan.
A source told the Sunday Mirror: 'All that pain caused to other people was for nothing. The relationship ended almost immediately afterwards. It seems a terrible shame.
'Alan had known Kristina for eight years and their wedding was perfect. His fling with Sarah ended all of that. It's hard to understand why he did it.'
The dancer and the footballer, who now plays for Notts County, met in 2007 when Ms Macmillan took part in a photoshoot with the England football team.
The pair were friends for years before finally becoming a couple and they married at Peckforton Castle and said personalised vows, which they had written themselves.
But the footballer is believed to have started seeing the 43-year-old motor trader after meeting her at a gym.
A spokesman for the couple previously said they were keen to avoid speculation and would make no further comment on the matter.
They are said to be considering divorce proceedings.
Smith played 19 games for England during his career.