Speaking of gayly written things, I usually don't let people in on my complex criteria for how I judge people for using bad gay tropes but I'm a lot more forgiving for circumstances setup by the game. TS4's (or another game's) code isn't gonna be the perfect ally, and does it have to be? The Sims' use of fluid sexuality has given players a lot of leeway to play sims as fully gay, even if IRL sexuality is NOT fluid for anyone, for even a majority of people.
Problematically use "gay with an exception" as a way to explain away the fickle desires that the game pops up? I'd have done it differently and hope you do better in the future, but if your story is written using the games' circumstances anyways and for many other things, I at least understand where the excuse comes from. Spend months deliberately planning to kill your only lesbian character, rejecting the advice of multiple people who say "don't do that"? You don't deserve my sympathy and without an apology, will never get it.