Why does Jane feel uneasy when she hears that Mr. Bingley is returning to Netherfield?

Mrs. Bennet hears from Mrs. Phillips that Mr. Bingley is planning to return to Netherfield in a few days. Jane tells Elizabeth that she does not want to see much of him. Elizabeth, however, after having seen him while on vacation with the Gardiners, is sure that he is still partial to Jane, and thinks that perhaps Mr. Darcy may have told Bingley that he now approves of the match. Bingley's return to Netherfield is obviously for the purpose of seeing Jane again, ascertaining whether or not she still loves him, and proposing if it seems that she does. The obstacles to Bingley and Jane's marriage were merely external ones, and once those obstacles were removed, their union was inevitable.