sentimentality (n.)

1749, "pertaining to or characterized by sentiment, appealing to sentiment rather than reason," from sentiment + -al (1). At first without pejorative connotations; the meaning "too tender-hearted, apt to be swayed by sentiment" is attested by 1768 (implied in sentimentality). The French word is said to be from English. Related: Sentimentally.

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]

"tendency to be swayed by sentiment; sentimental habit of mind," 1801, from sentimental + -ism. Originally especially in reference to the philosophy of Rousseau.