How do I keep my players happy?
The easy answer to this question is to give them what they want, but that’s not always easy, so it mostly comes down to the degree of flexibility you’re willing to offer. If a player can see that you’re making a genuine attempt to at least meet them in the middle, rather than outright rejecting their request, they’re more likely to accept your decision or, at worst, only become Concerned.
Players will also give you every opportunity to correct your mistakes before escalating their unhappiness to a more severe state. You will be prompted to take action through Inbox messages, Backroom Advice, and direct interactions with players when a player is unhappy, and you can often rescue a situation before it gets out of hand. You do need to be proactive in doing this though; simply leaving things to run their course will rarely work out in your favor.
Treating Team Leaders and Highly Influential players with the respect their status deserves also goes a long way to maintaining a happy dressing room, and the same goes for ensuring players in a sizeable and powerful social group are kept happy. If these players become unhappy, it can quickly spread throughout the squad, far more so than if a fringe first-team player has a concern. You don’t always have to bend over backwards to give them what they want, but a common-sense approach is always advisable: acting fairly and honestly is of tremendous help.