Not sure I would drop too much coin on first bike. She will drop it, everyone does with the first bike. You can find lots of first gen Ninja 250's 2000 through 2007 that are in great shape and cost from $1000 to $2500. If she drops it there is less plastic to fix and aftermarket parts are a dime a dozen because of how long they ran that model (87 to 07).
2am and I'm heading to bed when I hear a loud muffler outside. I look out the window and see an SUV parked and 2 assholes running from it towards the cars parked on the street around the corner. I retrieve my carry pistol and confront the driver from my front door....pretty short conversation....mostly 'get the fuck out of my neighborhood and don't come back'....very motivating words from a man brandishing a firearm. His buddies overheard our conversation and came running back to his truck. He took off so fast one of them fell out before he could get the door shut.
Nope still have it, it's turned into a loaner bike - one friend had a minor accident and is waiting on insurance; and my roommate broke some bolts replacing the clutch - so they've used it so they can still go riding. Not the same as their R1's but it's a bike...
I started on a Ninja 650 as my first bike - I'd never ridden before either, but I am significantly taller than the OP's spouse so I may not be a good reference. (I still have it & it's for sale btw). I thought the 650 was a good start since it had more power for highway speeds than a 250. Just my 2 cents... Good luck, I'm glad to see another lady getting into riding.