Yeah, I also don't like the BDLS (Biggus Dickkus Love Syndrome), as cheap excuse to have sex scene. But I would say it is cliche for a few more characters than just Kath and Emily. I mean for Emily, just as for Frisha, were both saved from harm by MC. Emily twice from bandits and Frisha from being raped by Dave. So it's somewhat understandable that they fell for MC without much more of courting and convincing. BDLS was but another reason. Although Emily could grief Marcus a bit longer and have a bit more of a struggle to replace him with MC, because right now it feels too soon and too easy, but that's the shortcut for the sake of porn I guess.
Rick's Mother, Verana (Or was it Verona? Well, either way it was a pizza kind of name) have BDLS too, which MC can discover by spying on her and later by fucking her in the workshop (Which i did by mistake by picking wrong option).
It was some time since i did dwarven questline, but I think Gawina also have BDLS, although "rekindling" her inner fire is a pretty smart, although somewhat funny, explanation for it.
Also, almost all girls by having sex with MC are getting, sooner or later, BDLS. But at least they didn't jump on it right after they saw it, so that a great plus.
As for Isha, I'm surely not going to help her. But she's a powerful witch and only one person close enough and capable of teaching MC magic, so "helping" her long enough to become more powerful is pretty reasonable goal before taking her down. Althrough Sabrina might cause some problems without some convincing first.
Well, then I'm happy for ya you finding this type of content enjoyable. Although I have to disagree. Games have already predetermined endings like books, a headcanon, but we cannot just skip to the last page, because we need to cheat to do so. The difference between game and book is the interaction part. Instead of reading about it, we can be in the heat of it. Everything what happens ouf of headcanon is but a illusion, a creator's answer to "what if" question made by his mind.