If you, the second poster here, turn back before she decides to stop? It will only set her new stop point closer to barn. You need to ride horse until it balks, and then the best course is to sit it out.
To both of you.
Don't take horse back to barn, don't handwalk horse, and don't fight with horse. Just sit. And no talking, or anything. Also is good idea to make sure you have gone to bathroom, and don't drink anything before leaving out.
Do not battle this. If you do, you are giving horse something to get mind set on, and that is having its way. Merely sitting there, and facing direction you want to go is the key. If horse tries to spin, turn, or what have you? Just turn until you are facing YOUR direction, and then go back to sitting.
As long as horse is not fighting you? You will be more than happy to sit awhile. Key here is that once horse decides it is better to move your way, you merely continue your ride, no praising, petting or babying, and no talking.
At intervals, cue horse to go forward. If it does, then ride. If it doesnt'? Sit. And remember NO praising, patting, or talking to horse at all. Horse is merely doing what it is supposed to be doing, which is going forwards at your direction. It has not cured cancer. So keep your mouth shut, and act very matter of fact.
You can also, if you can mount from trail yourself, carry small bit of grain, and feed horse away from barn too, but this must be further than eyesight of barn, and not the first time horse balks too. That only reinforces a boundary of where horse won't go.
And if horse is timid, you need to step up and be more of a leader here, as horse will feed off of you.
And work on strengthening your leadership skills with horse, being more dominant in terms of your mindset, and actions.
Horses make me a better person.