What exactly is a novella?

I must confess to being averse to the literary form called the novella.  What is it?  Apparently it is longer than a novelette (never heard of that till just now when I looked it up on wikipedia) and shorter than a novel.  I've never been quite sure why we need this distinction.  Different people give different lengths for a novella. Some say as few as 10,000 words, some say 70,000 words is the upper limit which is quite a long book in my opinion.  To Kill a Mockingbird, Of Mice and Men, The Old Man and the Sea...all of these are considered by some to be novellas

Some would say a novella does not try to accomplish as much: one plot, one major character.  They tend to be bundled in books with short stories.  A friend recently recommended and loaned me a book by Jim Harrison called Farmer's Daughter.  I was anxious to get to it and had a space saved for it for fiction February.  Guess what? That's right:  three novellas!  The first was titled Farmer's Daughter and it was short and dealt with one story line and one subject and reflected Jim Harrison's characteristic love of Montana and Arizona and the rural life.

The Farmer's Daughter was about Sarah the daughter of a transplanted Montana Farmer. She has a  horse and befriends an old ranch hand who is dying after her mother abandons her and her father.  She learns to shoot.  She is raped by a traveling musician and plots to shoot him in the head. She hunts, and she falls in love with a man three times her age.  She leaves Montana for Arizona.  While I enjoyed the story and will probably read the other two novellas...I have to put my finger on something that bothers me about Harrison and other male writers about the way they portray women.

They always seem mystified by how women behave.  They paint them as these foreign beings being stymied by their lives.  It almost seemed as though Mr. Harrison put himself into the body of Sarah and kept questioning what she would do.  It was as if he couldn't understand her.  It might be that the reader is to figue out that Sarah was going through difficult times and she was confused, but it only felt like Jim Harrison was confused.  As a reader, it was hard to separate the male writer from the young woman.  Quick, I would love to know of a male writer who has a knack for portraying women? Not as mysterious beings who can't make decisions, but as whole characters who may not make the right decisions but seem to know what they are doing.  Ideas please?