Punctilio

[…]–but, a-propos, ſaid he—Shakeſpear is full of great things—He forgot a ſmall punctillio of announcing your name—it puts you under a neceſſity of doing it yourſelf.

Source: wiktionary

The country was rigorous in exacting my compliance to my engagements to a punctilio, but equally careless in performing her contracts with me; and why so?

Source: wiktionary

It was only whispered, for something unutterably mournful no less than distressing in this spectacle of a man showing himself to be so entirely the vane of a passion enervated the feminine instinct for punctilios.

Source: wiktionary

[I]t seemed strange to be engaged to so charming a girl and yet go through with it as if it were simply a social duty. If one had n't been in love with her at first, one ought to have been at the end of a week or two. If Ambrose Tester was not (and to me he did n't pretend to be), he carried it off, as I have said, better than I should have expected. He was a gentleman, and he behaved like a gentleman, with the added punctilio, I think, of being sorry for his betrothed.

Source: wiktionary