Did it ever strike you as strange that your cat will pick up on any little change in your house - move a chair 6" and she will notice it immediately - but you can do major changes to your appearance and she won't even react? I just cut nearly 5" off my hair today and does Molly even act like she sees it? Nope.
I suppose we are strange creatures to them. We change the color of our clothes every day, we use differently scented soaps and perfumes, we put on makeup and glasses and jewelry. Molly probably quit trying to figure me out a long time ago.
By the way, I cut my hair because I found out that Locks of Love can't use gray hair, and neither will any other hair donation organization I investigated. I was growing out my hair to donate it, but the organizations can't use mostly gray hair. None of them wanted hair with more than 5% gray, and I passed that cutoff when I was in my 20's. The Locks of Love website said they will take gray hair and sell it to recoup operating expenses, but I'm not going to cope with growing out my hair for that. Heck, if it was just going to be used to raise money I'll send them a check.
I feel much more like myself with my hair above shoulder length again anyway. And no more catching the end of my hair under my purse shoulder strap, or in the car door (I kid you not, and it hurt - the wind caught my hair and blew it out the opening just as I shut the door) or under the seat belt shoulder belt, or tangling it up and pulling it when you turn over in bed. How do longhaired people do it?