SM has major issues with a terrible protagonist and poor primary narrative, theres a lot to unpack concerning whats so inexcusably fucked up about its structure, plot, and the inconsistent main character. Its a prime case of "death of the author". But like a diamond in the rough there are things worth salvaging and its not good to throw out the baby with the bathwater.
Theres no excuse for treating a character like Lise the way she was treated by the narrative or Theo. When the facts about her as outlined in the plot aren't in alignment with her treatment both by Theo and the structure of SM itself in a satisfying or sensical way, and when the apparent morals of the story are proved hypocritical and inconsistent by their own contents, and when characters are not portrayed or given proper credence by the narrative in a way thats consistent with the reality of their experiences and qualities as factually stated by the plot of events, and its not fair in its consideration of those facts in relation to other characters, then SM itself becomes a failure as a work of fiction.
SM suffers from a lot of these problems and it results in the unsatisfying feeling it leaves you with and the sense of wasted potential. Which is why for the sake of artistic integrity it is worthwhile to correct these mistakes by capitalizing on that potential and not let it go to waste.