How do you know?

I have said it before and I will say it again, Men and Women just don't understand each other (need to make a mental note to actually sit down and read "Men are from Mars, Women are from Venus"). I just get so scared that James and I are in this relationship simply because we are there (if that makes any sense). How do you know when someone really loves you? Do they respect you, do they do romantic things for you, is your every happiness their every happiness? Is it all about sacrifice, or is it about acceptance? I think it is probably all of these things, which makes love a very confusing thing for a person so young. I always said that if I didn't feel like I wanted to be in our relationship 100% then I didn't want to be in our relationship. But now that we have been through so much, is it okay to have doubts? Is it okay to feel like sometimes you just aren't sure that you see yourself with this person for the rest of your life? When asked today if I still was planning on marrying James, I paused , why did I pause? Is it that I am not ready to marry him? It is not that I don't want to be with James, but I think that if he was asked the same question he might have to stop and think about the answer himself. I guess I am just scared of ruining a good thing. We don't have to be married. I like what we have now. I guess what I am ultimately getting at is, how do you know when you are with the person who you are supposed to spend the rest of your life with? When do you decide to take the big step? I really used to see myself with James for the rest of my life. I could see us being married, taking trips, having more children, being a family, growing old (you know all of the old cliches). I am just not sure how clearly I see that anymore with recent developments. This is something that I guess James and I really need to think about. I am not sure how to talk to him about it though. He doesn't like to have these kinds of conversations and he gets mad when we talk about our relationship and where it is going. Maybe I should consider counseling?