In Brave New World, how does the confrontation between John and Lenina demonstrate their differences?Brave New World by Aldous Huxley

In his book The Art of Loving, the
renowned psychologist Dr. Erich Fromm wrote about what he termed "the Don Juan
syndrome."  By this Dr. Fromm meant the person who has a sexual relationship with a
person for an erotic release.  However, with this syndrome, afterwards there is always a
letdown and the person seeks again the heightened eroticism to satisfy feelings of
dissatisfaction and desire for something emotionally meaningful.  Yet, each time the
person engages in the act simply for prurient reasons and for release, he or she is left
empty.  In the dystopia of Brave New World, the
encounter between Lenina and John is no mere solitary episode, but rather a pivotal
incident that underscores an intrinsic theme of Aldous Huxley's about the loss of
humanity in the inhabitants of the New
World.

When the sexual act becomes an outlet
for one's anxiety or disastifaction or one's ability to recognize that an infatuation
may mature into love, that act becomes empty as Dr. Fromm points out in his book. 
Lenina, as representative of a world in which true human emotions are conditioned out of
people, has lost her true humanity.  For, she does not understand the meaning of her
feelings for John--while that true human emotion tries to burgeon in her heart. 
Instead, because of her dehumanization, she interprets her feelings as need of simple
release.

Of course, John is repulsed by what he views as
promiscuous behavior.  He calls her the "strumpet" that she would be in a Shakespearean
world, or even the Malpais society.  For, John's education in romance has set boundaries
for people based upon human respect and dignity.  He reacts violently to Lenina because
he subconsciously recalls the women of Malapais and their reactions to Linda after she
took men as her lovers.  He mutters lines from Shakespeare about unfaithful women, with
the "drums and rhythm" of the fierce poetry encouraging his action.  Underscoring
Huxley's theme of the loss of humanity in the New World, this outburst anticipates his
later passions after leaving London, especially his violent act of
"atonement."