I've always thought about relationships this way. If I can't see myself with this person for the rest of my life, I'm not wasting any more time than I need to with them. Simple as that. I have far more important things to worry about right now.
I don't feel comfortable talking about my thoughts and feelings. I can't make people understand so I just stopped wanting to make them. So I am very grateful for friends who realize I've got something going on without me telling them.