Why do people use online dating
An act of self-injury which might make sense if understood as a suicide attempt become all the more difficult to comprehend when the self-injurious person denies that they are trying to kill themselves and is telling the truth. What are they trying to accomplish when they harm themselves?
Though loose, psychotic-style thinking is not something that everyone has experienced directly, at least the idea that people can experience hallucinations and delusions is familiar to most.
Some of them will self-injure so as to generate a strong sensation that is capable of bringing them back to feeling something again. Not all numb dissociated people will use physical pain to "return"; some will use other strong sensations such as are afforded by drugs or sex, etc. Sometimes, people who self-harm are not skilled at using language to describe their inner experiences.
This can be because they are not particularly good with words.
Sometimes an aspect of a person's chaotic internal experience is that feelings and thoughts build up a subjective state of tension or arousal that motivates people to do something to take action to reduce that tension or arousal.
Cutting or burning one's self can, apparently, serve such a tension-reducing function. I read an account of a young woman who was consumed with suicidal thoughts which pushed her towards a compulsive feeling that she should end her life.