1650s, "of or pertaining to the fact of being male or female," from Late Latin sexualis "relating to sex," from Latin sexus (see sex (n.)). Meaning "pertaining to copulation or generation" is from 1766; sexual intercourse attested by 1771; sexual orientation by 1967; sexual harassment by 1975. Sexual revolution attested by 1962. Sexual politics is from 1970. Related: Sexually.
word-forming element making abstract nouns from adjectives and meaning "condition or quality of being ______," from Middle English -ite, from Old French -ete (Modern French -ité) and directly from Latin -itatem (nominative -itas), suffix denoting state or condition, composed of -i- (from the stem or else a connective) + the common abstract suffix -tas (see -ty (2)).
Roughly, the word in -ity usually means the quality of being what the adjective describes, or concretely an instance of the quality, or collectively all the instances; & the word in -ism means the disposition, or collectively all those who feel it. [Fowler]
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Harper, D. (n.d.). Etymology of sexuality. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/sexuality