Great, a nicely composed discussion post. Let´s get into it. Pardon, but Veronica not wanting kids was simply the last straw which broke the camel´s back. Their relationship was already heavily taxed by the gym problems.
From what I remember the only bits of information we've been given about their relationship is that Veronica did not want kids while her wife did, I don't remember at which point do they talk about the relationship being heavily taxed by gym problems, would be great if you could remind me where that is mentioned.
Sorry, but that is not true. It has been mentioned in the game that Veronica could start anew with another gym and live her dream, never needing to go through the crap Kath throws her way.
Losing the current gym would surely feel devastating, but she can recover and live her dream with a more fitting gym. Even Samson, who is responsible for most of her woes (not all, the gym was already in dire straits even before Samson began to meddle), said that she could simply walk away, put all the baggage into the "shitty life experiences" drawer and start fresh, living her dream with the second gym.
But that she does not do so because of her massive stubborness.
If you read my earlier post you know that I mentioned the emotional attachment part, why it is important to have such attachments and that it is not easy to let go. But Veronica is drowning in debt, lost her dream marriage in great part because of the gym woes, even making yourself a sexual clown for bored rich people will not help long. She has to get rid of that poisoned rooms.
And see above why Veronica could still live her dream.
Again, as much as it might seem logical and I could agree with you that Veronica should just let go of her current gym, for her it means letting go of much more than just 1 thing, it's the same as admitting defeat, and she would much rather fight for it even if it means debasing herself, so yea, is she stubborn? of course, but pretty much all the Carnations are.
I don't remember exactly how it's said in game, but even Edwin at one point says something along the lines of: "The thing Kat was looking for in the carnations is that they all share 1 thing, Single-mindedness."
And hey, maybe the good ending for Veronica is to let go of the gym and decides to move forward and start a new one later on, or she actually manages to fight for it and keeps it a float. It's all up to however TD wants to handle that, and I would be fine with either or.
Also I hate to be asking for proof in such a long game, but where is it implied she could just let go of this gym and start a new one? I don't remember that either, it could very well be I'm just forgetting but I'd love if you or someone else could provide the proof of this being said ingame, I'd love to reread that part.
Also you mentioned her personality being very average and boring compared to the other girls in the game, and I'd also have to disagree with that, she's a very well built character and I find her personality very complex, she's the only girl we see put up such a strong facade, and we've also seen her crumble down in tears, to me her character is 10x more interesting than Rose's for example. Ofc, what you consider average or not it's up to you, so there's no point on arguing this, but I just wanted to give my own opinion.
edit:
Eh, Veronica implies her dogged attachment to the gym did play a part in breaking up her marriage.
Coupled with a few other comments from her, it gives me the impression her issue stems less from the fear of losing what remains of her glory days (although that's still a factor by her own admission), and more from the act of losing itself, as if her ego was formed entirely around the concept of winning, and losing undoes her very sense of self.
Hmm I might need to reread that then, but now that you mention it, it does ring to me that at some point she might mention something like that.
and that other stuff you mention, I agree with, that's the whole deal with her character, she does not want to accept defeat.