Edith Wharton said this quote

He could not imagine being bored by Susy -- or trying to escape from her if he were. He could not think of her as an enemy, or even as an accomplice, since accomplices are potential enemies: she was some one with whom, by some unheard-of miracle, joys above the joys of friendship were to be tasted, but who, even through these fleeting ecstasies, remained simply and securely his friend.