You know the type. Everything is horrible. It's all drama and it's all bad. You want to listen. You want to help. But your suggestions fall on deaf ears. They don't want help. They just want to complain. And drag you down with them. Don't let them do it. Be strong and say enough is enough.
To clarify, this does not mean that you should ignore your friends when they need help. We all benefit from the assistance of others. But when you find yourself hearing the same complaint again and again ("he's so mean to me") but no response to your suggestions ("why don't you tell him that this bothers you?"), you can be sure the person is comfortable playing the victim. They don't want to change. They enjoy the drama. And they like the attention that it brings them.
But you can't save someone who won't take action to save themselves.