This was abrupt, yes, but it's not unexpected. I think this is paced fine, I never even guessed it was based on a novel, and trust me, I can usually tell. The pacing is always off, the artist usually glosses over important plot points, introduces characters like we should already know them, there's usually a disconnect between narration and the image, etc. Like a webtoon I read recently, crimson karma, if that isn't a novel adaptation, I'll eat my hat. Korean adaptations usually do a good job, but Chinese adaptations are the worse, Japanese can go either way.