It happens a lot to me too. I sometimes use the editor to remove the unhappiness. Not every time because if i have neglected to do it fair enough. But if i have done as promised but still get complaints i just make him happy again via the editor. Not ideal i know but makes it a bit more playable. Another slight issue is that if a player is really tired so i chat to him about resting him next match, he agrees. But when i play the next game he is devastated to be left out?