You are mostly correct. However, it is an emotional/mental disability that is often manifested in unusual sexual activity. Weiner is the classic malignant narcissist. Read up on narcissism and you will find that often, those so afflicted, engage in unusual sexual behavior -- even perverted -- one way or another. They either withdraw from sex, withhold it from their partners, or become overly active, even addicted to sexual activity. When addicted to sex it is because they feel power over the women they engage in sex with (either actually or via the Internet), and they want their adoration. Those two emotional needs are stimulants and they cannot live without them once they start.
It becomes their drug of choice and the addiction is very strong. Often narcissism is rooted in some early family dysfunction. Men have issues with their mother, for example...either hating her, or having been abused emotionally or physically by her. So they try to regain their self confidence and self respect by abusing women via acts of sexual perversions. Who knows what is at the base of Weiner's problem, but as with alcoholics, there is usually something that they are trying to either cover up emotionally, or drown memories, or get a power high...or all.
With the Internet...and, I must say, thousands of willing partners (women and men who have no self respect and might even be narcissists themselves), they can engage in sexual arousal and masturbation privately, undetected, and without actually having physical contact with a live partner. It is the perfect playground for a pervert, as we all have seen over and over. And, in their minds, the narcissist never believes he is cheating because he feels there is no human contact. They are masters at twisting and rationalizing, manipulating and convincing others that their beliefs are normal or to be considered accepted.
And there is no magic, real "cure," they can only elect to daily work to control their urges. It is extremely hard for these men and women afflicted in this way, to refrain from the activity that has become their supply of emotional highs. Temptation is always there and they will lie over and over to hide their "habit" because they have become so dependent on the thrill that a moment of arousal brings them along with the satisfaction of using someone else whom they consider a lesser individual. All of this in order to gain some instant self satisfaction, even if there are major risks involved.
On June 7, I posted:Report: Anthony Weiner Coached Woman...comment 37
Weiner is the classic, text book example of a malignant narcissist who has absolutely no real sorrow about what he did. Truly, he is angry that he was caught by those who he feels are lesser individuals than he and they spoiled his fun - if only for a while. A narcissist who is perverted in a manner that he must surf the net or Tweet women to get a thrill, will not stop totally. He can't. He is sick and dependent on the "high" he gets from being a sneaky cyber sex pervert. He will halt for a while, but he will return somehow