'Man's love is of man's life a thing apart. Tis women's whole existence.' This is taken from the poem of-

Man's love is of man's life a thing apart. Tis women's whole existence.

In the light, mock-heroic style of Beppo, Lord Byron found the form in which he would write his greatest poem, “Don Juan”, a satire in the form of a picaresque verse tale. The first two cantos of Don Juan were begun in 1818 and published in July 1819. Byron transformed the legendary libertine Don Juan into an unsophisticated, innocent young man who, though he delightedly succumbs to the beautiful women who pursue him, remains a rational norm against which to view the absurdities and irrationalities of the world.

Several other quotes from Don Juan by Lord Byron - (Oxford References)
Sweet is revenge—especially to women.
Don Juan (1819–24) canto 1, st. 124

Pleasure's a sin, and sometimes sin's a pleasure.
Don Juan (1819–24) canto 1, st. 133

Man's love is of man's life a thing apart,
'Tis woman's whole existence.
Don Juan (1819–24) canto 1, st. 194

[Source: Britannica, Oxford dictionary]