If girl A is a more experienced rider, and girl A's horse is a more difficult to handle horse, while girl B is less likely to be capable of handling girl A's horse, since girl B can't even warm up her own horse....then it's perfectly fair. But that might not be the case, there are far too many variables here.
God, do you KNOW how many times I had to re-read that to make sure I had my A's and B's in the right places? *lol*
If Girl A and Girl B are comparable level riders, on comparable level horses, then each just ride their own horse, if it's an issue. Goodness me.
LOL can we give names to Girl A and Girl B so it's easier to understand? How about Girl A is Hailey and Girl B is Tara?
Are Tara and Hailey friends? Do their horses need the same amount of discipline? Is there a risk involved for Tara to ride Hailey's horse, moreso than if she were to ride her own horse? Is Hailey perhaps worried about liability? Do Hailey and Tara have the same experience levels? Why does Tara think Hailey is not offering to let her ride her horse? Sorry to take you back to seventh grade health class lol, but is Tara perhaps being too passive and not voicing her opinions, so that Hailey doesn't know that Tara wants to ride Hailey's horse? And lastly, why the crap won't Tara and Hailey ride their own darn horses LOL?