Does love grow

I know we all get married for different reasons but when do you, how do you know if it's turned into love. I married my friend because he had asked me to so many times but when I finally said yes I think it was more of gratitude. He stood by me when I lost my mom, I had so many destructions at that point but he kept me in line. We now have 2 kids and I know I love him and he loves me, but I always wonder on what could have been.