Thank you for waiting.
It sounds your friend or partner has sexual problems and possible underlying problems such as sexual addiction and anxiety
/depression based on your report. He meets many women and lies about meeting women to you. He collects/purchases 800 womens panties.
He may have a paraphilia.
A paraphilia is a condition in which a person's sexual arousal and gratification depend on fantasizing about and engaging in sexual behavior that is atypical and extreme. A paraphilia can revolve around a particular object such as underwear or around a particular act. The focus of a paraphilia is usually very specific and unchanging.
People with a paraphilia depends on that object or behavior for sexual gratification.
Yes, he needs treatment for his sexual problems and possible mood disorder such as anxiety and OCD.
Once he acknowledges he has a serious problem, he can change his problems.
Cognitive-behavior therapy (CBT) or Psychoanalytic therapy can be helpful for him in changing his addiction. He may find a psychologist specializing in addiction and CBT.
However, you said he is not seeking treatment for his problems.
It must be very difficult for you to be with him unless he receives treatment.
I would advise you to get support from a counselor for your own if you can't make decisions right now.
You may need courage to leave this relationship.
For your mental health, you may need to start seeing a counselor or therapist to deal with him.
Please let me know if you have more questions or I have overlooked any. Warm regards,