This is quite confusing: Mary seems to be quoting here from a play that was written more than hundred years after her death.
Edmond Rostand (1868–1918) wrote his smashing-hit play Cyrano de Bergerac in 1897. It is based on the true story of Cyrano de Bergerac (1619–1655) written in beautiful French verse.
Cyrano, both the real and the fictionalised, had a mega-nose, which was admired and ridiculed far and wide.
Due to his low self-esteem, he didn't dare express his love to Roxane, his beautiful cousin. She, in turn, was in love with Christian, a handsome, though slow-witted musketeer.
José Ferrer and Mala Powers in the movie Cyrano de Bergerac (1950)
Being the gentleman officer that he was, Cyrano did everything he could to ensure Roxane’s happiness. He whispered sweet verses in Christian's ear, and Christian repeated them in Roxane’s ear. When Christian died in battle and heart-broken Roxane retreated to the monastery, Cyrano paid her weekly visits, in which he continued to entertain her with his wise verses.
Only when he's about to die in her arms does she realise that Christian's verses were Cyrano’s and she laments: “I loved one man, and now I've lost him twice!
It's impossible that Rostand was acquainted with Mary's diary, of course (since I am the first to ever set eyes on it) so I think we can conclude that this is a case of subconscious plagiarism.
That is, if we believe in the existence of subconscious.