as a child, a lot of kids ask "why does it hurt?" they think the hurt stops. it doesn't.
when the first grader comes home crying because they skinned their knee, they ask "why does it hurt?" of course, they're not aware of the white blood cells rushing to the area to keep possible diseases out of the body. they aren't aware that the bleeding is the body's form of cleansing itself. the parents do know that. but they don't tell them. they just say "because it's dirty," clean it, and the child is happy again. because the pain is gone.
when the seventh grader comes home, crying because they were teased because of their weight, they ask their parents "why does it hurt?" they aren't aware that those kids teasing them are probably insecure about their own weight. they aren't aware that the teasing is made out to bring the bullies up a level. they're just aware that words hurt and they have newfound insecurities. the mother reminds the child that they're beautiful the way they are and the father reminds them that they never need to change. for anyone. the child is sent away with a healing wound, that hurts less.
when the high school senior walks home, after their boyfriend or girlfriend gently breaks up with them because they aren't going to the same college, the tears stream down their face. they ask "why does it hurt?" they aren't aware that they will change heavily over the course of the next four years. they aren't aware that they will probably reconnect, at some point, and they will not meet the person they once loved. the person they meet will have changed drastically, as they have. the mother affectionately holds them, and the father supplies ice cream and laughs, and over the course of the next four years, the pain goes away.
when the housewife comes home to see her husband kissing a woman in their bedroom, suddenly, she is that first grader who skinned her knee again. except, it's not her knee that's bleeding, it's her emotional heart. then, she is the seventh grader, insecure about her weight. and that insecurity comes back in a landslide. lastly, she is the high school senior, reliving that first heartbreak. she is crying, on the phone to her sister, asking "why does it hurt?"
when the same housewife attends her second husbands funeral, years later, tears stream down her cheeks. she relives every memory. every kiss. every hug. every show of affection. she asks the preacher "why does it hurt?" in answer to her question, he gently tells her that the hurt never stops. because it gets better, but only because she forgets. but new hurt is added to old hurt, and each new hurt brings up the old hurt.