she felt that Frank Churchill didn't really care for her.

She came to this conclusion because he left suddenly after the picnic without explaining anything.

CH:44

I was so astonished when she first told me what she had been saying to Mrs. Elton, and when Mrs. Elton at the same moment came congratulating me upon it! It was before tea -- stay -- no, it could not be before tea, because we were just going to cards -- and yet it was before tea, because I remember thinking -- Oh! no now I recollect, now I have it; something happened before tea, [.....]so, when Mr. Elton came back, he told us what John ostler had been telling him, and then it came out about the chaise having been sent to Randalls to take Mr. Frank Churchill to Richmond. That was what happened before tea. It was after tea that Jane spoke to Mrs. Elton."

Till then Jane had been avoiding the acceptance, but when she heard *before the tea* that Frank Churchill had left, she spoke to Mrs Elton about accepting the job *after the tea*.