So here's my theory on masochistic kinks in general.

• Sexual pleasure can be an escape from pain or negative emotions
• Using sexual pleasure to escape from some pain, via the mechanism known as "classical conditioning" makes that pain a trigger for the sexual response. It creates an (at least one-way) association from the pain to the sexual release.
• Anticipation of sexual release triggers preparation for it, ie arousal

So I'm gonna talk about some dark shit here. Let's say a woman is about to be killed by a mugger in an alley. He's beating the shit out of her because he's a sadist and the mugging is just an excuse to himself, to get violent with people. She, or that monster part of her that comes out when her life is threatened, to protect her, decides to try and reframe the situation as sexual in order to maybe survive. So she seduces him. It works. He stops being violent with her. It's like, it's an act but she knows it has to be convincing enough to save her life so she gets into it, to be convincing.

It's just fire together, wire together stuff. Painful, ugly, shameful, or disturbing experiences get associated with later sexual "reward" (in the technical, operant conditioning sense of the word), and that gets reinforced through repeated activation if the person indulges in it.

TL;DR:

• Some pain or a negative emotion experience precedes sexual release in time
• Preceding in time creates classically-conditioned association. Pain now activates sexual pathways
• One thing that creates consistent preceding-in-time relationship is using sex as escape from negative emotions
• One example (given above) is woman who escapes being killed by having sex with attacker
• Another would be a guy who is humiliated and it's unbearable so he jerks off just to feel something positive