Though I'm happy Isabelle was added by the manhwa for this long training trip arc, knowing that she wasn't there in novel is still kind of sad because it means she should meaningless, in the end. It's kind of weird for this manhwa, having a character be present and developed for so long, but for no reason. Unless the manhwa changes the whole story, but I wouldn't really expect that. Normally she should be the prime romance candidate after all this time, but that especially seem exceptionally unlikely knowing she was just a minor character in the original source. Of course it's entirely possible there won't be any romance whatsoever, despite the MC clearly being interested in such things and women often flirting with him, in which case it doesn't really matter in the big picture.