Purpose of the Over-The-Shoulder Shot
The OTS shot connects the characters, whereas a single shot will disconnect your characters. Gives the effect that both characters are on the same page. It also is used to show the perspective of the character from the angle of their shoulder.
What film aspect shows a disconnection between characters?
A single shot shows the disconnection between characters. This shows that both characters are not on the same page or having a disagreement. Using single shots isolates your characters.
How does the director of this scene show the disconnect of the characters?
Applying a single shot. When they were both on a different page about the subject the director used a single shot to disconnect the characters.
What eventually totally isolates the female character?
Ford and the hosts have a connection whereas Teresa does not. This establishes to the viewer how alone Teresa really is.