I don't know your favorite song or flower
Or favorite food or drink.
I don't know what time you go to bed or get up in the morning.
Or how often you think of me.
I don't know your favorite color or your favorite type of animal,
Or if you even like animals.
I don't know your favorite time of day,
Or day of the week, for that matter.
But I know I love you.

Jeff Fleischer

http://www.poemhunter.com/poem/but-i-know-i-love-you/