poor old Cathrine Morland ,when she is "ignored "by Henry Tileny at the theatre in Bath.

This picture above shows the interior of just such a theatre in Yorkshire-The Theatre Royal ,Richmond-see link below.

It was brightly lit, they were opposite each other in boxes,and he "failed" to notice her!;

On the beginning of the fifth, however, the sudden view of Mr. Henry Tilney and his father, joining a party in the opposite box, recalled her to anxiety and distress. The stage could no longer excite genuine merriment — no longer keep her whole attention. Every other look upon an average was directed towards the opposite box; and, for the space of two entire scenes, did she thus watch Henry Tilney, without being once able to catch his eye. No longer could he be suspected of indifference for a play; his notice was never withdrawn from the stage during two whole scenes. At length, however, he did look towards her, and he bowed — but such a bow! No smile, no continued observance attended it; his eyes were immediately returned to their former direction. Catherine was restlessly miserable; she could almost have run round to the box in which he sat and forced him to hear her explanation.... NA, Chapter 12

Most provincial theatres were quite imitmate:Henry and Catherine were within probably no more than 20 feet of each other.Hmm....