Well, to each their own, I guess, bcs I like such side-stories. I've never felt about it bad or like I'm splitting some couple. Maybe exactly because of those changes in background, which allow you not to feel guilty. These details in characters' lives and their past make the story more natural for me. I personally less like stories where all ROs are just some stereotypical superficial things with no background whatsoever, who are all from the very beginning head over heels with the MC, no matter if you persue their routes or not.
P.S.: for me it is strange to be so opposed to the idea of side routes for ROs. Like, yeah, I'm not interested in your route, but you can't want anyone else. ???
Hey, it is even opposite for me, I have trouble to pursue other romance route when I know that my previous interest would stay lonely and sad that MC rejected them :D. Like in Ascension by Rinmaru, i was really courious of other romance routes but never tried them because ZANDER IS WATCHING and I just cannot :<. But I am not sure how I feel about Daelyssa...I see the point that routes should be consistent, but I also like diversity, the more different stories are to discover the better for me. In my personal, really personal opinion I would love to see Daelyssa romance on Daemon route and my head canon would be loving polyamorious triad ;)