If you're playing on PC you can console dumb your other half
Supposedly when you meet them after that they tell you how much they hate you every time.
On consoles, you'll have to take her to a battle she can't win, I'm afraid there's no other way. Followers die all the time, they have a mind of their own and they charge in battle even when you're trying to sneak attack. I've had 3 who died in battle, 1 who got bored of waiting for me and just left (Iona) and 2 dogs who died very quickly because they don't know when to stop attacking. Plus 3 or 4 horses, inc Frost, who either died in battle or just disappeared randomly.