In "Brave New World," John's perception of male/female love is from his only source of knowledge: William Shakespeare. When he watches Lenina sleep, her perfect beauty enthralls him as Romeo is enthralled at his meeting of Juliet:
On the white wonder of dear Juliet's hand, may seize/And steal immortal blessing from her lips/Who, even in pure and vestal modesty,/Still blush, as thinking their own kisses sin.
Uttering the words from Romeo's half of the sonnet of Act One,
If I profane with my unworthiest hand/This holy shrine... (I,v,88-89)
John indicates that he has an idealized conception of love as one holy and pure. He is ashamed of lustful thoughts that enter his mind:
Detestable thought! He was ashamed of himself! Pure and vestal modesty...
A fly buzzes by him, symbolic of sin, "trying to steal immortal blessings." Then, when Lenina offers herself to him, John is repulsed and calls her a "strumpet." Having set Lenina as an ideal, she can only disappoint him, even if she were to display morality of which she knows nothing. For, she has been conditioned to think that "everyone belongs to everyone" although she does prefer to only go with one man at a time and for some time.
In contrast to this idealization of love between man and woman, John truly understands filial love since he has real, human experience of this love. His love for his mother is absolutely genuine; this veritable love is later mocked in the New World of artificial realities in which conditioning erases true emotion that is too dangerous; it causes unhappiness.