They need to implement a rule where if they leave on compassionate grounds they should forfeit a percentage of the contract (they have already earned) they agree to due to hardship felt by the club they are leaving. This fee can be paid by the player or the club he is going too.
Or a percentage is withheld until a certain milestone of the contract is reached. ie.(3 year deal, retainer held until 2 year mark)
this would go both ways. For example if the club doesn't offer the rest of the contract they have to pay the player a percentage of the contract.
obviously early release and such agreements would still be allowed.