I found this on Ray Ortlund's blog at The Gospel Coalition. He quotes a guy I've never heard of who wrote a book in 1909.
“Paul had rich and original conceptions of love, which he had learned from Christ. Christ had loved him in his unloveliness. He had been patient with him in his blindness. His love had been the love of which Matheson sings, ‘O love that will not let me go.’ It had been the love of which Paul himself sang (1 Corinthians 13:4-8). The man who had this ideal of love realized what it was to be a friend.
It was to love unselfishly. ‘The third time,’ he wrote to the Corinthians who had been such a source of care and grief to him, ‘I am ready to come to you, and I will not be a burden to you, for I seek not yours but you. I will most gladly spend and be spent for your souls.’ ‘Though,’ as the King James Version reads, ‘the more abundantly I love you, the less I be loved’ (2 Corinthians 12:14-15). He loved men for their own sakes, not for what they could be to him selfishly, though he rejoiced when they poured back such friendship love as his in return. But that was their friendship, not his. His friendship love gave and bargained for no return. It coveted good for its objects and was ready to purchase this with pain.”
Robert E. Speer, Paul The All-Round Man (New York, 1909), pages 68-69.
I find myself so often wanting something back from my friendships instead of focusing on them and loving them.