I don´t remember where, but I believe it was in "Reluctant Empress" by Hammann, I have read that Sophie suffered a lot when she was a young and charming princess and she knew she was to marry Franz Karl. Her old nanny was so worried, cause Sophie was in deep sorrow and crying all the nights. So, the old nanny, who really loved tenderly the princess, tried to find support for the young Sophie speaking with queen Karoline. But Karoline said nothing but "What do you want?The entire issue was a choice made by the Congress of Vienna!" (I´m not quoting exactly, but working from memory...).
When Sophie realized there was not a way out from the engagedment with Franz Karl, the poor little thing was strong enough to say: "I´m determined to be happy...and I will be".
This purely emotional reaction from Sophie always shocked me. She grew up knowing well her duty as a princess. And Franz Karl was not a ugly man; he had a simple mind and he had not character, but he was a gentle prince. Above all, he was the son of an emperor and also a pressumptive heir of his elder brother, the epilectic and mental retarded Ferdinand. I can understand Ludovica suffered a lot because she was in love with prince Miguel of Portugal and she was forced into a marriage with a cousin, Max, who frankly told her he has in love with a common woman and he was to marry her following the orders of his father, Duke Pius. But Sophie was not in love with anyone...