Pity parties

Let me start out by saying I mean no offense to anyone, but sometimes I get annoyed when someone is telling me a sob story. Its annoying because I can't understand what their problem is. Lately I have been sitting in a group, watching, and there has been at least two people who are pretty much constantly crying. I find myself thinking "God, stop crying, get over it," I won't name anyone or talk about their problems. I could never be a psychologist, I have a hard time understanding their sides, I do try to understand them, but I have never experienced what they have gone through. I get angry at myself because I can't bring myself to care or pity them, I don't know how to respond. Instead of the appropriate responses, I just smile or laugh, roll my eyes when no ones looking, and this tends to hurt peoples feelings.