How would you know if your girlfriend loves you?

I have had my girlfriend for two years and i have to ask myself if i realy love her sometimes. I feel like i don't love her sometimes, love is not some walk through the park, love is tuff stuff. Love can be the hardest thing in the world, the hardest thing in the world to keep right, and true, and pure. But when i think about my future with my girl, that's when my doubt goes away. Because, even though there maybe girls who are more exciting, funnier, more self confident, easier to get along with, my girl is the one girl that i wanna share my life with.