This doesn't come to us as a surprise, but here it is anyway: Gwyneth Paltrow and Chris Martin had an open marriage. Do they even know who's the father of their kids? Anyway, People, says that their 10 years of marriage included some form of extramarital fun.

People says that for years their marriage has been a mess.
Several friends tell PEOPLE that the pair, who were married for 10 years, at times had an “open” relationship. “They were physically separated and emotionally,” says a Paltrow insider. Adds a close friend of the 41-year-old actress: “They have been on and off for many years. The marriage was falling apart.”
UsWeekly basically echoed what People said. So why divorce anyway?