You're NOT a Therapist
It's a good thing to be there for your family and friends when they need to vent or when they're going through a tough time; however you need to know when to say enough is enough. If you have a friend and/or family member that is constantly discussing issues that they refuse to resolve themselves, then you need to put an end to the theraputic sessions.
It's not healthy to constantly listen to someone complain about a situation, when they're not doing anything to resolve or make the issue better. Eventually, you will take their sadness and depressive state as you're own. If someone really cares about you they will not bombard you with their problems that they have no intentions of resolving.