I love how 'my nails remain unchanged' is Maria-sensei's way of working out whether drunk fuckery happened last night
That... is not what happened, though? Quite the opposite, she was worried that she may have hurt her during the "drunk fuckery" because she had not cut her nails.
Oh whoops. Different interpretations, then. I assumed Maria thought 'unchipped fingernails' = 'did not finger a woman last night'
On the next page, she's specifically apologizing for probably having hurt Mei.