In 2007, Sergio Denis was dating a girl named Melisa Durán, when she was selected to participate in the TV programme Gran Hermano 2007 broadcast by Telefe. Just a week after entering the house, Durán cheated on Denis with another contestant of the reality show. Her infidelity caused both the breaking up of the couple and her expulsion from the house, with more than 80% of votes against her.
On 14 May 2007, while on tour in Asunción, Paraguay, he suffered a decompensation that caused a cardiopulmonary arrest. Denis was admitted to the Sanatorio San Roque of that city unconscious and without vital signs, but he was resuscitated. The following day, the doctors disconnected him from the artificial respirator, and after a period of observation, he returned to his normal life.