The ones who want someone to do 'everything' for them are often just opportunists that see kindness as something to exploit.
sometimes because you've done everything for them and they haven't learned to do anything for themselves.<br />
OR because they've come to believe that you enjoy (or don't mind) doing everything for them, and those are the roles you've chosen in the relationship.<br />
OR because they're narcissists and don't see that others have needs or feelings.<br />
in any case, the remedy is open nonjudgmental discussion, including what you will & wont do in the future. then stick to it.
When they let you down - you don't have to go down.
If you've had to do everything for someone that should be an indication they're not capable of doing for themselves which should eliminate all chances of being let down because you'd expect it. You can't volunteer to do for others and expect something in return. The whole process of doing something without being asked is that it's a gift, not a loan. Be content in the fact you're a giving person and leave it at that. If you don't want to be let down than don't volunteer yourself.
Thus is the way of the world.
^I'm still trying to figure this one out...There are certain friends I have that haven't let me down like this. I think those who constantly do are toxic people to be around.