Dave Eggers, A Hologram for the King

Full excerpt:
Live long enough and you’ll disappoint everyone. People think you’re able to help them and usually you can’t. And so it becomes a process of choosing the one or two people you try hardest not to disappoint. The person in my life I am determined not to disappoint is you.
I believe the protagonist says this to his daughter, if I recall correctly. I could be wrong. I like this quote because it shows one way that we love another.