The players, as far as I can see it, only have a limited number of 'reason I am unhappy'-excuse cards in their rolodex.
I strongly suspect that very often, the player 'has trouble adjusting to the x lifestyle' or gets 'homesick' because we promised, once again, way too much to them. First team play, but they only play half the matches, things like that make a player unhappy, too. But if they play quite regularly, if not all the time, they can't really say 'I want to be an FTR'. Or once they've come to the club, they notice that some second team numpties earn the same wage as they do. Not all players will immediately resort to 'wants to be paid what he is worth', because in all fairness, they already get that. They want to get paid what everybody else gets, but that excuse-card doesn't exist.
How often did you sell a player who was homesick to a rival, where he all of a sudden forgot all about his beloved home-country and was happy to stay at the club? Happened very often to me.
It's just a minor game-limitation, as far as I can see it.
(My personal record was set with a Dutch player, whom I signed for Lidingö, who just couldn't get used to Sweden, a thing he decided upon on the very day he stepped off the plane in Arlanda (Stockholm airport IIRC)!!!

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