I agree. One great 'compensation' of Ferdinand's penchant for peasant women was that I don't think any peasant girl would have the audacity to challenge Amalia and she, after all, quickly earned the nickname 'La Signora' among her subjects (a reference to being bossy, no doubt). And it also appears that Ferdinad did his womanizing elsewhere or at least did not make any of his mistresses very conspicuous, as far as power/infleunce was concerned (I doubt if his womanizing was kept secret from his subjects though). MT's advice to Amalia to give her husband 'freedom' point to that. I seem to have read at an Italian site that Ferdinand's carriage could be seen at the house of his mistress but it was also clear that he continued to have sexual relations with his wife (mentioned as no longer pretty yet.....). And as mentioned, no doubt Amalia would've gotten rid of any interloper who dared to take her place (she was very haughty!). That said, Ferdinand didn't seem to produce any bastards from his numerous affairs. At least, I have not come across any reference to illegitimate children yet.
I also think that despite Ferdinand's complaints to his grandfather in particular about Amalia (and she was indeed a handful, being extremely capricious and dominating) and his letters, he (more or less) had the same view as her with regards to being free from any unwanted interference. The blackmail and the threats, not to mention the curbing of his religious fervour, apparently did not sit well with Ferdinand. Amalia also mentioned that A LOT of people try to influence Ferdinand but as she was the most visible, I guess all the blame went to her. No doubt she had great influence on him throughout their marriage, despite their problems. I just went back to read Amalia's biography in Parma's library and it says that Duke Ferdinand named (grandson) Charles Louis as his heir and appointed Amalia head of the regency for their grandson. Ferdinand never met his grandfather Louis XV nor his uncle Charles III of Spain. There were plans to make him travel to France and Spain (mainly to separate him or rather break-up his marriage to Amalia) in 1771-72 but nothing came out of it.... so yes, Ferdinand appeared to prefer his wife over his relations abroad.

If Amalia was so nasty, unfaithful and troublesome for him, surely he would've taken that chance and filed for divorce as Spain and France wanted. No doubt he would have custody of his daughter Caroline.
Anyway, I just read that Ferdinand was a great fan of the Italian dish anolini, which originated in Parma. He was not only fond eating it but also made it himself (the pasta and filling, too), with the help of his daughters.

I guess Amalia wasn't the only one who dared do things considered not proper for their station.