Washington Square: Lavinia Penniman’s tenderness

A year later, Dr Austin Sloper hasn’t “budged a hair’s-breadth from the position [he] took up a year ago” and “Catherine appears not to have budged an inch either; she is equally fresh; so we are about where we were before.” (Ch.27) 
Washington Square starts with a mind game between Dr Sloper and Morris Townsend, and turns into a battle between the doctor and his daughter Catherine. This is something everyone knows about, and we also know that later Catherine matures and gradually sees through everyone and resists to all of them in her own way. 
What interests me at the moment is the aunt, Lavinia Penniman. She is sentimental, irritatingly meddlesome, tactless, stupid and shallow—so far in the book, she is some kind of comic relief. But now I’m starting to notice something else. 
Look at this conversation, which takes place when Catherine comes back after a year in Europe.

““I have seen a great deal of him,” said Mrs. Penniman.  “He is not very easy to know.  I suppose you think you know him; but you don’t, my dear.  You will some day; but it will only be after you have lived with him.  I may almost say I have lived with him,” Mrs. Penniman proceeded, while Catherine stared.  “I think I know him now; I have had such remarkable opportunities.  You will have the same—or rather, you will have better!” and Aunt Lavinia smiled.  “Then you will see what I mean.  It’s a wonderful character, full of passion and energy, and just as true!”” (Ch.25) 

Isn’t that just ridiculous and very inappropriate? 
The narrator assures us that it’s not what we think it is. 

“Mrs. Penniman had not a particle of jealousy of her niece.  For herself, she felt as if she were Morris’s mother or sister—a mother or sister of an emotional temperament—and she had an absorbing desire to make him comfortable and happy.  […]  She had never had a child of her own, and Catherine, whom she had done her best to invest with the importance that would naturally belong to a youthful Penniman, had only partly rewarded her zeal.  Catherine, as an object of affection and solicitude, had never had that picturesque charm which (as it seemed to her) would have been a natural attribute of her own progeny.  […]  Sentimentally speaking, therefore, she had (though she had not disinherited her niece) adopted Morris Townsend, who gave her opportunity in abundance.  She would have been very happy to have a handsome and tyrannical son, and would have taken an extreme interest in his love affairs.” (Ch.27) 

Mrs Penniman prioritises Morris’s interest like he’s her son, the narrator says, but I’m not so sure.  
Look at the letter she sends to Morris Townsend: 

“…I miss you dreadfully; the house seems so empty without you.  What is the news down town?  Is the business extending?  That dear little business—I think it’s so brave of you!  Couldn’t I come to your office?—just for three minutes?...” (Ch.28) 

Does she not sound like a lover? 
As I go back, I find more interesting details: 

“… in the bottom of her heart she permitted herself the observation: “That’s the sort of husband I should have had!”  He was certainly much more imperious—she ended by calling it imperial—than Mr. Penniman.” (Ch.6) 

Later: 

“Mrs. Penniman rose with considerable majesty.  “My poor child, are you jealous of me?” she inquired.” (Ch.17) 

Note that people at this time and Henry James himself had a distinction between being jealous and being envious. 
What exactly, then, is Lavinia Penniman’s interest in the whole Sloper vs Sloper vs Townsend conflict? 
Slowly she takes Morris’s side, and doesn’t object when he decides to give Catherine up.