Girl1: Look at <Girl3>, she's wearing white clothes!
Girl2: Ugh, weakness disgusts me. Only weak girls don't wear black in the summer.
Girl3 (looks at <Girl1> and <Girl2> and thinks): "Poor girls, that's masochism!
To be excited by the object of ones unrequited desire's cruelty to loved ones or third parties as a means of personal subjugation.
To enjoy the cruelty of the powerful over the powerless when powerless yourself.
When the one you can't have insists on being cruel to the one you've got, and you cum in your pants? That's not even masochism, it's masochism by proxy.
When the sexual enjoyment derived from one's own pain/humiliation clashes with their want to end their own life. It usually forms into wanting someone to hurt them to the point of fatality, masking it in a sexual light.
Her: "I want you to choke me."
Him: "Okay."
Her, later: "Oh my god, please step on me."
Him: "Okay...?"
Her, even later: "Step on me and just crush my spine, dude!"
Him: "I'm mildly uncomfortable now. You're bordering on suicidal masochism."