I have a best friend, and we are too close to each other. Its our decision for this type of relation. He is having a girlfriend and before this relation I was normal but after this type of relation I am expecting more things than him and some time he could not fulfill it. Then I'll get angry at him and thought that he is selfish. What should I do?

When you see that what you are doing is wrong, or unhealthy, you stop doing it!