The Protagonist as a Round Character?

Is it possible?

"Tomorrow at four"

Can the main character of popular Gilded Age novel like Wharton's The House of Mirth not develop throughout the story?  This question has puzzled me throughout this recounting of this fraction of Miss Lily Bart's life.  Does she change, become a better person?  In my opinion, no.  I think she has a deep desire to lead a life with Selden, but she just cannot bring herself to do it.   The life she would live with Selden would be moral and enjoyable--something no other bachelor can offer her at this day in age.  "...the sight of Selden's writing brought back the culmination moment of her triumph; the moment when she had read in his eyes that no philosophy was proof against her power.  It would be pleasant to have that sensation again...no one else could give it to her in its fullness..."  (Wharton, 113)  However, being Selden's wife, to her, means surrendering all the hard work she has put into becoming a wealthy mannequin wife to a man like Rosedale or Dorset (if he gets a divorce).  The pressing issue is that, after meeting Selden, she does not want anyone else as a husband.  Therefore, she is unwilling to commit to the other men.  Lily traps herself in her own cycle of indecision.  She cannot choose happiness because she knows wealth, and she cannot choose wealth because she knows happiness.  (Oh, what a tangled web.)  As one can see, Lily wants to develop but cannot, and it's her own fault.  She stunts her own personal growth.