Hayzed Pastures said:

Have you had a vet/dentist come and check her teeth? Id say start there if this is a new issue. What bit have you been using that she seems to not like?
As for bitless bridles - id say a S or Flower hackamore or a decent bosal. I dont know of actual "bitless bridles" to recommend but ive used the 3 ive recommended and like them a lot

FirstLightFarms said:

I have a flower hack I like a lot! Very gentle but more stopping power than a halter.

If you want to keep the halter action though, there are side pulls that do the same thing but are more bridle-looking :)

Ironclad Roan Estate said:

I have good luck using a little s hack on a couple of my mares, although I do vetwrap the rope noseband to make it softer and wider.

Gray said:

Hope the flower hackamore works out for you!

Just to add, in case you wanna change it up ever or if someone else is looking for options here-

Two Horse Tack makes some nice cheap (~$50) sidepulls. You'll get pretty close to the halter action with one, and they seem pretty popular with the trail crowd - you can get biothane (easy washing) and bright colors for safety.

Milestone Equestrian also just came out with great sidepulls. Between 100-150 but still a great price point for what you get. She's done a lot of research on making them anatomical, relieving poll pressure, etc.

The main thing I'd advise against with bitless bridles are the crossunder ones, like a Dr. Cook - they're notorious for not releasing pressure, so the horse ends up with a vice grip on its face that doesn't release when you do.

Nothing wrong with a flower or little S hack, either!

Happy trails!