Trust is a complicated issue...
"Trust," to me, is equally fraught. Especially when someone says "Do you trust me?" Or, even worse, the more defensive, "Don't you trust me?"
For example: "Don't you trust me to do the taxes?" (I chose this honor of the month.)
This would generally delivered a way to mean: "Don't you think I'm honest enough?" But one can completely trust someone's honesty while, at the same time, knowing they are terrible at math. The "No" answer might be off-putting in the latter case, or hurtful in the former, but unless one goes out of one's way to add more context, the word "trust" can't bear the load of the question.
In a way, asking Sharon "Do you not trust your sister?" is far more complex than "Do you not love your sister?" would be.
The Curmen sisters are dealing with it all the best they can.