Is It Time?

I've been in and out of serious relationships, but none of them have really made me want to stay and say "alright, I can do this with you."  I've met such great guys and when it came down to fully committing, I back away.  Each time I bring a guy home to meet my family, I break it off.  I can never fully put my heart in anything.  I ask myself, "Am I a robot?"  I don't feel anything, no let me rephrase that, it's not enough to make me stay.  But why is that?  Why do I have feel like I have to settle down?  I'm in my 30's, not married, dating, and in college.  I've never had the urged to settle down, have a family or do what people call unselfish things.  Is there something wrong with me? Or am I just being to picky?  I don't know what it is.  I just want to be happy and happiness isn't easy to find.  I'm happy where I am at right now and that's something feel really great about. So I'll worry about love and what society calls the norm when the time comes.