Sometimes you need to take people out of your life. Some people can be a drain on your energy, or they are quite bothersome—some may ask for money or take much of your time for deeds. Of course, you should try to help people but you should pull the plug when they take advantage of you. It isn't good or healthy for either of you. They shouldn't have to depend on others and you cannot be too selfless or else you'll put yourself in a bad predicament.
There's always a balance with things and if there are imbalances in your relationships then it's best to either make them aware that you cannot be there for them or end the relationship. I'm not saying things should be 50-50, but I am saying that you must protect yourself and them from these imbalances.