How did 'piety = piété' and 'pity = pitié' diverge and evolve?

Question

This Quora question motivated this. Do the Etymonline entries below imply that the connotation changed in Old French (and so even before English)? I pose the question also for the equivalent French nouns, because it appears to concern both English and French.

How did 'pity = pitié' evolve to connote negativity? As per the bolded, how did 'piety = piété' affect 'pity = pitié'?

pity (n.)
early 13c., from Old French pite, pitet "pity, mercy, compassion, care, tenderness; pitiful state, wretched condition" (11c., Modern French pitié), from Latin pietatem (nominative pietas) "piety, loyalty, duty" (see piety). ...
English pity and piety were not fully distinguished until 17c.
Transferred sense of "grounds or cause for pity" is from late 14c.

I heed the Etymological Fallacy. But what are some right ways of interpreting th etymology, to make it feel reasonable and intuitive?

Answer 1

You might find this entry in the OED on 'pity' {noun} useful:

"Etymology: < Anglo-Norman pité, pittee, peté, peti, Anglo-Norman and Old French pitet, pitee, pitié (Middle French pité , pitié , French pitié ) compassion (c1100), piety (15th cent.; rare) < classical Latin pietās (see piety n.). In branch II. probably after Middle French pieté piety n.

"The sense of Latin pietās ‘piety’ was in post-classical Latin extended so as to include ‘compassion, pity’ (Vetus Latina), and it was in this sense that the word first appears in Old French in its two forms pitié and pieté . Gradually these forms were differentiated, so that pieté , which more closely represented the Latin form, was used in the original Latin sense, while pitié retained the extended sense. In Middle English, both pity n. and piety n. are found first in the sense ‘compassion’, and subsequently in the sense ‘piety’, and the differentiation in sense is not complete until the 17th cent."