I think when I learn that someone I enjoy is in a relationship my attitude toward them drastically changes.
Why do you think that is? Do you use it to learn to be better in relationships?
Those guys who are in a relationship could set an example for me to follow.
It is understandable that you don't want to be involved anymore when you find out the other person is in a relationship. It does change how you feel and you could be judge by others too.
I don't prove it to anyone or talk about it, I just don't like to date or pursue anyone who is in a relationship.
Well, that is wrong. Why would you want to steal someone from their happy relationship? How would you feel if someone stole your loved one away from you?