I actually agree that having the husband still living would have been more interesting. I just couldn't make it work in the overall framework.
If we are supposed to actually like and respect the husband, then I would hate for Tara to cheat on him. If we don't like/respect the husband, why would Tara be married to him? We're suddenly looking at some dark backstory with forced marriages etc. [I almost gave up on Project Myriam early on, just because I couldn't stand Anthony.] Having Tara already be in an open relationship right from the start would undermine the corruption angle, and would need more exposition/explanation.
So the only option left would be if Tara's husband essentially gets corrupted/liberated along with her, with a LOT of renegotiations of relationship parameters etc. I would love to play that if its well-written, but I'm not sure whether I could write that. And if I tried, it would crowd out everythingthing else. Hence, poor Robert had to die.
It's definitely a tough balance, especially if you're writing the character as you don't have quite the same level of detachment a player would. Personally I can stay detached even if it's a good character getting the short end (one reason I can play NTR games, I don't immerse myself and put myself in the cuck's shoes! I'm just a third party watching some poor guy get cucked
). I also completely see where you're coming from, if Tara married a good man it's hard to watch let alone write that man having something so unjust happen to him, and if she married an asshole well as you said how do you justify their marriage? That being said, there is the route of husband starting off good but then turning into an asshole, but personally for me that loses some of its spiciness. There's also the traditional "husband-is-so-overworked-he-neglects-his-wife's-sexual-needs-oh-no-now-chad-is-fucking-her" that NTR games use, but of course
they all use that. Anything open is at best swinging and at worst cuckolding but not cheating, so those are out as you say.
Now there is one possibility, but feel free to discount if it doesn't work with what you've got planned, is have her "start again" with another man. Perhaps there's a plot path where she meets someone who makes her doubt her current path of debauchery or something, players could choose to put her in a relationship and then cheat on him as her corruption is too strong. You'd run into some of the same problems as the still living husband path, but as it's a new relationship it might be easier to stay detached and/or justify writing him being cheated on (to avoid the real pain, have him stay clueless maybe). It's not by any means original but hey what is in porn games?
(Naturally I would expect her to regularly get knocked up with everyone and everything's baby but his
)