Bad news lads, I don't think I got what the game considers the "true romance" with Wenduag. Going over the guide again, I was supposed to get a cutscene after a random rest, where my guy talks to her about her daddy issues or something. I never got that because I probably picked a wrong dialogue option somewhere idk. Good news is that while I am pissed at my own inability to follow a fucking guide, I can't say I'm disappointed with how the romance turned out in the end. In fact, I like it a lot better than the other one.
From what I've seen of what Lagole posted here earlier, the """true""" romance ends up portraying Wenduag as an unstable and insecure loser whose daddy issues you cure with a good dicking (or scissoring, if you're gay). I specifically remember that one corny af line that went like "PLEASE DADDY GIVE ME PERMISSION TO BECOME A NICER PERSON" (paraphrasing btw) and that torpedos her whole character. Before, she is a hardass with a soft side, but now she is a pathetic poser that merely put up a convincing front. The problem is, you don't get into the Wenduag business for the emotional support gig, that's what Arushalae is for. You go for Wenduag for the boss bitch appeal, the tender moments you do share with her becoming all the more meaningful in contrast. She is the warrior gf for high test players LIKE ME, looking to take a break from the usual lovey dovey romances the genre is full off.
Fortunately, I got the conclusion to the romance I wanted, more or less on accident. I think this is just the regular romance ending. You still speedball the poison, pass out and have a chat when you wake up but instead of "DADDYYYY YAAASSS" Wenduag stays true to her character, telling you that, while she still thinks love is a sham, you mean the world to her and that while she still hates people, you're the one guy (or girl, if you're gay) she wants to be with. And if that's not the cutest shit then I don't know what is. She manages to articulate her feelings according to her own principles and stays herself, ultimately proving that she is strong after all.
No idea why the other variant is considered the better one. Goes to show how wrong a writer can get their own character.