Infinity.

I love all my friends so much that I want to collect them all into my heart, so that they can all live there and each have their own room and hang out with me and each other. But I also want my heart to be infinite, so that everyone, even strangers, can fit in it and have eternal happiness. But my heart cannot be so big because it would explode, and I like to believe that the world itself is my heart, with everyone, even strangers, living in it.