Mary's comments should be taken as a reflection on her own whiny character, not on LR. Mary is only satisfied if she is the center of attention, and while I'm sure LR is always civil and polite (probably constantly reminding herself that Mary was also the daughter of her dear friend LE, in order not to smack her), I am also convinced she would not go out of her way to amuse and placate Mary. Mary and her imagined disorders, when she is bored, remind me of Mrs. Bennet's nerves--though I must say that Mrs. B had more worries, what with the entailment and trying to marry off five daughters. Mary has two sons and is married to the heir of the Musgrove property, after all.

There may be fewer comments on LR in this section, but I think it is easier to see in these chapters why Ann loves her. (In the first four chapters, I think we are upset over her interference in Ann's love life, given the outcome--even if we understand her motives.) LR is indeed the one "truly sympathizing friend" who understands Ann's feelings on having to quit Kellynch.