Before I ever dated my wife, we spent about 5 years being friends. We were such good friends to each other that we would even give one another relationship advice (like we knew any better) to help when the other was having issues.
One day, I began to notice these crazy feelings I had. Though I loved her dearly, I began to notice that I would miss her more, think of her more, and want to give her more. I was falling in love.