Austrian father: not that unusual, if you consider that the captured enemy officers socialized a lot with the Prussian court ladies, were drafted as dancers and what not. (Unless Fritz especially gave order for the officers in question not to.) But it explains why she'd think he'd marry her after the war (according to Countess Camas), not during. Having just found the relevant entry in Lehndorff when you pointed it out, I guess this Countess H. is probably the same person. In terms of Lehndorff's negative characterisation, on the one hand, he does have a double standard and is prone to cry out "MESSALINA!" intermittently at young women behaving the same way noble young men do, otoh, he doesn't do this all the time (see the very positive entry about the Austrian Ambassador's mistress in 1756, for example, and with Countess Bentinck, he goes from bristling at her from liking her. So IDK how reliable his judgment is here. Otoh, what he's most angry about is that she's been lying to both the Queen and Countess Camas when they had promised to help her and handle everything discreetly, i.e. the unnecessary lie more than the sex, and it would make sense that this is what makes Camas herself annoyed with the woman, too.