I think Miss Austen does make reference to the Martins anger and frustration in ch. 21 when Harriet describes seeing Mr. and Miss Elizabeth Martin at Ford's.

"Elizabeth saw me directly; but he did not; he was busy with the umbrella. I am sure she saw me, but she looked away directly, and took no notice; and they both went to quite the farther end of the shop; and I kept sitting near the door!

[...] he looked round and saw me; for instead of going on with their buyings, they began whispering to one another. I am sure they were talking of me; and I could not help thinking that he was persuading her to speak to me

[...] presently she came forward -- came quite up to me, and asked me how I did, and seemed ready to shake hands, if I would. She did not do any of it in the same way that she used; I could see she was altered; but, however, she seemed to try to be very friendly, and we shook hands, and stood talking some time;

[...] I remember she said she was sorry we never met now;

[...] I found he was coming up towards me too -- slowly you know, and as if he did not quite know what to do; and so he came and spoke [...]"

Even Emma is caught by their feelings, apparent in their conduct.

The young man's conduct, and his sister's, seemed the result of real feeling, and she could not but pity them. As Harriet described it, there had been an interesting mixture of wounded affection and genuine delicacy in their behaviour.

She quickly talks herself out of pity for their pain by describing it only as a ambition disappointed. Blind Emma! She can not even believe her immediate acknowledge of good in others...