I read in Loomis's book and elsewhere about Fersen's aborted attempt to see her in Vienna. However, he was able to see her in England at Hartwell House in Buckinghamshire in 1809 and before that they corresponded. Loomis thought that she avoided him in Vienna because of the "affair" he allegedly had with her mother, but I think her Habsburg relatives were just very strict about who she saw, and Fersen was not on the list of people she could recieve, perhaps because of the gossip. He was welcomed by the Bourbons, as they all remembered him from Versailles, as he had been part of the diplomatic corps of Sweden to France. Marie-Therese welcomed him as a friend of both of her parents. (This was in Turquan's biography of the princess, I believe, or else in Miinergeride's "Son of Marie-Antoinette". Fersen, many believe, was helping M-T investigate the fate of her brother, Louis XVII.)