One of the ways she copes with life is music, specifically by listening to an artist named Doug Blackman; more specifically by listening to her favorite song by him called "The Day I Became a Ghost." Eliza is a music journalist, so she meets Blackman for an interview early in the book. Later she meets his son, Loring, who falls in love with her. On her birthday, Loring gives her the original sheet of paper (in a frame) that his father used to write the lyrics for "The Day I Became a Ghost" and Eliza begins to cry. When Loring tells her he was only trying to cheer her up, she says, "You did. It's just that, well, sometimes happiness hurts."
Sometimes happiness hurts. These three words seem like they belong together. Happiness comes in brief spurts and it often sneaks up on a person. Pursuing it rarely leads to capturing it and even when it does, it doesn't stick around long. But when happiness sneaks up on a person, especially when it comes from the actions of another person, it can feel so good it hurts. But actually I don't think it's the action itself that touches us so deeply as much as the thought that someone knows us so well that he or she is able to do something for us that strikes at the heart of who we are. Loring knew Eliza so well that he knew how to move her to the depths of happiness.
Sort of makes you want to go out and find a way to give someone you love a moment of happiness today, doesn't it?