It is not necessary to provoke people portraying a sympathetic ear. Showing visible signs of sympathy and compassion for the other person, you only encourage him to tell you everything that happened in his personal life sorrow and sadness. Try to steer the conversation to the other, neutral, theme. Show that currently do not have enough time for a serious conversation.
Determine the number of persons that you are willing to listen and take their emotional outpouring. Usually it is our closest people. With colleagues at work and with all the other friends try to keep your distance, built in itself a kind of boundary beyond which do not need to admit outsiders. Of course, if a person has a sincere grief, he is looking for sympathy, you can not remain indifferent. But if you are trying to impose all privacy concerns, you should stop the tough conversation.
Try not to give in to a request for advice on a particular worldly issue. Usually, people are very reluctant to use someone else's experience. It may be just an excuse to pull you into the next parsing conflicts. Try not to scroll mind other people's problems. Stop thinking how someone could help. Remind yourself that you have plenty of reasons for their feelings.
Do not hesitate to remind your friends that you have your own life. And it is no less interesting and just as worthy of attention. Learn to relax and get pleasure from the friendship. Relationships can be emotionally exhausting, not only, but also light, giving the mutual joy of communication.