That's why I'm a bit skeptical about Amalia having lovers.... no names were ever mentioned unlike Caroline.
But, considering her circumstances, that's very possible.
Here's a bit on Ferdinand and Amalia from the book Maria Theresa by Paul Tabori (1969):
Maria Theresa was said to have been distressed that Amalia's intended was educated as a philosopher... what would such a prince think of her sweet but not so intelligent daughter? Nevertheless, she agreed to the match. The Spanish ambassador boasted that Ferdinand would be the best educated ruler in Europe.
Ferdinand had a mistress when Amalia arrived! Very soon after Amalia arrived at the palace, he took her hand and brought her to the basement kitchen and asked her if she liked roast chestnuts and if she did, he'll get her some... then he introduced his mistress to her and told the two ladies to be friends! He assured Amalia that his mistress doesn't bite!
Amalia, of course, soon recovered her poise and ate the chestnuts and then they played hide and seek.
Ferdinand roamed the countryside all day and came only to the city to ring bells.
Du Tillot's complaints included Ferdinand's preoccupations with ringing bells and roasting chestnuts. Amalia, on the other hand, spent money like water and danced with peasant boys in the main square, went to the market to do the shopping herself and spent half the mornings gossiping with the market women there.
MT also sent Leopold from Tuscany to preach submission and economy to his sister. Of course, he wasn't that successful (even though Amalia was fond of him).
MT sent Count Rosenberg to verify the truth of such reports for she could not believe those things of her well-behaved and virtuous (at least in Vienna) daughter. Amalia told Rosenberg of her troubles there, then called Du Tillot a 'base wretch' and his mistress, the Marchioness Malaspina, a 'stupid goose'. The envoy was shocked-- where did she learn such language? Yes, she dismissed them for she wanted to have fun and wanted fun/gay people around. Then she sent her love to Mama the Empress.
Soon after, MT decided not to write Amalia and also did not to want to hear about her. It was said that Amalia wasn't bothered by this and the two continued their way of life. But Charles III was so angry he wanted to send troops to Parma to restore order there. But MT talked him out of it -- how can an army of occupation prevent the Infante from keeping a mistress and ringing bells and roasting chestnuts? The same would not prevent her daughter from issuing her crazy decrees and fooling around with the yokels. They could be certified as crazy but tha's too much of disgarce to both dynasties so just tet them go bankrupt by stopping the subisidies and perhaps they will change.
Ferdinand talked to Amalia to write MT and do something for they didn't have any money left in the Treasury and he didn't dare write Spain or France (I think this was the point when Amalia was pawning and selling her jewelry -- MT wrote Count Mercy in Paris about it). So Amalia wrote her mother, who was moved by her daughter's pleas and promises to change. A few days after, a large sum of money arrived from Vienna. But soon after, Amalia declared that they were happy with their way of life and that no one should interfere and refused to receive her mother's envoy. No messages for Vienna either.