Franz Stefan outlived Isabella, in fact, but if they had significant interactions, the biographies don‘t mention it.
Re: the Isabella/Joseph marriage, you also have to consider: in a total of three years marriage, she had one surviving child, two miscarriages, and a fourth pregnancy during which she contracted smallbox, had yet another miscarriage and died, painfully. 19th century biographies: „She appeared melancholy.“. Yeah, no kidding. I‘d be screaming from the rooftops, never mind sexual orientation.
I have a big soft spot for Joseph, too, but he and Isabella illustrate the big difference gender and the resulting power imbalance made. When Joseph finds himself in a marriage with a partner he does not want to be married to, for whom, in fact, he feels physical revulsion (i.e.his second wife), he avoids the woman in question. He can do that, because he‘s a) a man, and b) the co-ruling Emperor. And when after her death his mother wants him to marry a third time, he can point blank refuse. MT isn‘t happy, but as it‘s the aftermath of FS‘s death and Leopold has already produced male Habsburgs of the next generation, this is not a fight she keeps fighting. Both these actions would not have been possible for a woman, including MT herself when young. If FS had died during his ill-fated attempt at military heroics early in their marriage, with „just“ one or two daughters there, she‘d have had to marry again, no matter her grief. And she would have had to have sex with whoever the choice would have been.
So, in a fairer world Isabella wouldn‘t have had to marry Joseph to begin with, or at least could have told him that he might have fallen in love with her post-wedding (pre-wedding, before they met, he was nervous and really sceptical about marriage, which comes not just with being an 18 years old but an 18 years old Fritz fanboy) but she didn‘t love him), but she didn‘t feel anything of the sort for him, instead of having to fake love and joy. In the world they actually lived in, the odds were completely staked against Isabella, and like I said - I‘d have screamed from the rooftops.
(Footnote: I don‘t think Isabella would ever have confided into either FS or MT, not just because her own parents had been an example of everything bad a marriage could be, but because the whole point of Isabella being Joseph‘s wife ultimately was to produce an heir for the Habsburg dynasty (and to further the new Habsburg/Bourbon reconciliation). If not as Joseph’s wife, say, in the unlikely case of an anulment, there would have been no justification for her being there (i.e. with the yet unmarried MC) at all. Now if Joseph had been awful to her, or had avoided her (she wishes) the way he would his second wife, then she could have complained to his parents. But since he was being attentive and worshipping the ground she walked on, there was nothing she could have said that to an 18th century mentality would have justified a complaint.
In this context, it‘s worth noting that an older Joseph did go to the trouble during his visit to France to not just have that sex advice talk with Louis and the not listened to warning about the state of France to both Louis and Marie Antoinette, but he also when his sister first confided into him, and spelled out not just the excruciating details but basically depressedly went „maybe it‘s me, maybe I‘m just not hot enough or good enough“; he did try to cheer her up, build up her spirits and soothe her feelings by praising how elegant and beautiful a princess and hostess she was, and awkwardly told her that if she weren‘t his sister, her existence would totally convince him to change his mind about never marrying again. He was able to recognize unhappiness then, and that MA‘s problem wasn‘t just that she and Louis hadn‘t been able to have a child (though that was a big one for both political and personal reasons, obviously).
(Mind you, the next sister Joseph visited on that particular journey had worse. That was Marie Carolina who‘d married the King of Naples. I am still at the conference, but when I‘m back home I must quote you from Joseph‘s letters to MT about this fellow‘s sheer ghastliness. (None of them had met him previously, the marriage had been made via negotiations and proxy.) He was into cruel pranks and exposing his penis in society, among other things. BTW, if you‘ve ever read a novel or watched a film featuring the Nelson/Lady Hamilton tale, that was the court of Naples Sir William Hamilton was the British Ambassador at, and the Queen of Naples Emma befriended. Anyway, the reason I mention it is that an older, more mature Joseph - possibly due to his five ladyfriends, possibly simply due to more experience - does display a bit of a clue of how unfair life can be for a royal woman, and who knows whether or not he‘d have figured out how Isabella really felt and/or would have least tried to make everything a bit more bearable for her. But not at age 18 - 21 he wasn‘t. Without any bad intentions on his part, he was instead what she resented most about her life.)
Re: Random facts
Re: the Isabella/Joseph marriage, you also have to consider: in a total of three years marriage, she had one surviving child, two miscarriages, and a fourth pregnancy during which she contracted smallbox, had yet another miscarriage and died, painfully. 19th century biographies: „She appeared melancholy.“. Yeah, no kidding. I‘d be screaming from the rooftops, never mind sexual orientation.
I have a big soft spot for Joseph, too, but he and Isabella illustrate the big difference gender and the resulting power imbalance made. When Joseph finds himself in a marriage with a partner he does not want to be married to, for whom, in fact, he feels physical revulsion (i.e.his second wife), he avoids the woman in question. He can do that, because he‘s a) a man, and b) the co-ruling Emperor. And when after her death his mother wants him to marry a third time, he can point blank refuse. MT isn‘t happy, but as it‘s the aftermath of FS‘s death and Leopold has already produced male Habsburgs of the next generation, this is not a fight she keeps fighting. Both these actions would not have been possible for a woman, including MT herself when young. If FS had died during his ill-fated attempt at military heroics early in their marriage, with „just“ one or two daughters there, she‘d have had to marry again, no matter her grief. And she would have had to have sex with whoever the choice would have been.
So, in a fairer world Isabella wouldn‘t have had to marry Joseph to begin with, or at least could have told him that he might have fallen in love with her post-wedding (pre-wedding, before they met, he was nervous and really sceptical about marriage, which comes not just with being an 18 years old but an 18 years old Fritz fanboy) but she didn‘t love him), but she didn‘t feel anything of the sort for him, instead of having to fake love and joy. In the world they actually lived in, the odds were completely staked against Isabella, and like I said - I‘d have screamed from the rooftops.
(Footnote: I don‘t think Isabella would ever have confided into either FS or MT, not just because her own parents had been an example of everything bad a marriage could be, but because the whole point of Isabella being Joseph‘s wife ultimately was to produce an heir for the Habsburg dynasty (and to further the new Habsburg/Bourbon reconciliation). If not as Joseph’s wife, say, in the unlikely case of an anulment, there would have been no justification for her being there (i.e. with the yet unmarried MC) at all. Now if Joseph had been awful to her, or had avoided her (she wishes) the way he would his second wife, then she could have complained to his parents. But since he was being attentive and worshipping the ground she walked on, there was nothing she could have said that to an 18th century mentality would have justified a complaint.
In this context, it‘s worth noting that an older Joseph did go to the trouble during his visit to France to not just have that sex advice talk with Louis and the not listened to warning about the state of France to both Louis and Marie Antoinette, but he also when his sister first confided into him, and spelled out not just the excruciating details but basically depressedly went „maybe it‘s me, maybe I‘m just not hot enough or good enough“; he did try to cheer her up, build up her spirits and soothe her feelings by praising how elegant and beautiful a princess and hostess she was, and awkwardly told her that if she weren‘t his sister, her existence would totally convince him to change his mind about never marrying again. He was able to recognize unhappiness then, and that MA‘s problem wasn‘t just that she and Louis hadn‘t been able to have a child (though that was a big one for both political and personal reasons, obviously).
(Mind you, the next sister Joseph visited on that particular journey had worse. That was Marie Carolina who‘d married the King of Naples. I am still at the conference, but when I‘m back home I must quote you from Joseph‘s letters to MT about this fellow‘s sheer ghastliness. (None of them had met him previously, the marriage had been made via negotiations and proxy.) He was into cruel pranks and exposing his penis in society, among other things. BTW, if you‘ve ever read a novel or watched a film featuring the Nelson/Lady Hamilton tale, that was the court of Naples Sir William Hamilton was the British Ambassador at, and the Queen of Naples Emma befriended. Anyway, the reason I mention it is that an older, more mature Joseph - possibly due to his five ladyfriends, possibly simply due to more experience - does display a bit of a clue of how unfair life can be for a royal woman, and who knows whether or not he‘d have figured out how Isabella really felt and/or would have least tried to make everything a bit more bearable for her. But not at age 18 - 21 he wasn‘t. Without any bad intentions on his part, he was instead what she resented most about her life.)