Now that you talk about it, this is one of the things that really annoyed me with KoD. It started strong with Sabia AND with some teasing about what could Neve do sexually wise or not and then they just decided to add more and more secondary characters to the story when I just wanted to see more of Sabia AND Neve. Worst thing? the best content with Neve & Sabia is non canon/bonus content.
I'm pretty sure the split was not amicable. I doubt Sierra would work with Nomo again even if they did come back, and has proven she doesn't need to.
I know... I think Sierra is a hard worker/writer and Nomo could just not match her work ethic yet I think they were a great pair of creators. Nomo's art is great, yes, but it's more than that, it's a more streamlined gameplay too and a better overall pacing. I tried the games of Sierra and I think, of course this is only my opinion and personal preference, the pacing is just too slow, she loves and values game mechanisms too much for porn games and her games are actually difficult, this is not something I'm looking for when I play a H game, I just want cool characters, nice story and hot content/scenes.