Assuming that's the reason, the fans are not to blame. When previous Barça captains like Xavi or Iniesta wanted to leave, they announced it directly to the fans at a press conference. And they spoke privately with the board. Not in a burofax. And in no case do they hide, without giving public explanations.
But I doubt very much that this has anything to do with it. According to the press (assuming the allegations are true), the affected players were Xavi Hernández, Carles Puyol and Gerard Piqué, not Messi. And neither Pique nor any other player has done anything like this.
And it also goes against Messi's interests. If you want to leave, but the contract doesn't let you, first thing you do is meet with the president and negotiate.