I'll try to be more specific. I'm not talking about 'slice of life' novels, but action-packed, cultivation, fantasy, dungeons and shit kinds of novels where romance isn't the focus, but still have that subtle/romantic subplot that develops gradually or during the late parts of the novel. A good example would be 'Throne of Magical Arcana'. Of course, I'm asking for good romantic subplots. Then again, it's not like you can expect a good romance from the trash that's been piling up recently, but hey... as long as it's passable, I'll take it.
hmm there is a korean novel called "SSS-Class Suicide Hunter" the romance subplot is very good and you will love FL, there is also a murim arc which for me was what sold me the story well. the author's writing is pretty good although it's not CN I think you'll like it
IT would be Everyone Else is a Returnee , mc and the love interest develop over time and this is a late romance novel where they get officially together near the end
Spirit Vessel Spoiler: Many reader don't know So thw mc ain't reincarnated, he died and his lover sent his fragment of his soul (partial memory+changing it a bit done by her) mc in past life was central figure in his era. Past plot; his homeworld also central place in which at a time the secret of immortality will open (come up monolith, hole in dimension for that place but need many sacrificied aka bloody road, before the hole to the secret of immortality open, the outsider 'sent spy not cannonfodder but the strongest three in all outsider (heroine).....both go romance and the male eventually knew that she was one of the outsider, so he proposed I'm not participating in war between me (homeworld) and you (invader) both agreed and went recluse in North Sea, times past and war not only diminished, but burned even more vigor till the corpse drifting to the North Sea, he decided to not abandoned his people......mc vs heroine (Sword Goddess) both the same realm but mc just a few people vs invader around 12 and 3 of them the same powerful as him and each have top of the food chain treasure Vessel with different ability.... He defeat one and couldn't kill it so seal and to prevent it being open he split his soul as a guardian.....but he died by the sword of heroine, since he betrayed the pledge and participated she also participated and as apology she split his pitiful (remaining soul) and grab Vessel from his ally to sent him in Reincarnation Vessel (she wish if not now together maybe in another timeline)......time past she knew she failed to get the secret of immortality (kind of false, there ain't real immortality), so she guarded the place of him with her ending the war and till her death, before her death she created a persona, you know when many people adore something, something that should not existed being born out of people mind, so she ending the war and made many statue as people to adore and her persona born (as long as people remember her she will stay existed) but the persona ain't her so she made secret art that imbued all her memory in resonance to the statue, and she also reincarnated but not born in her homeworld but in her lover / mc world (so both will not difference camp)......times past and at the time of chapter 1 a few billions had past...... Many reader thinks he old so he should wise,....he ain't real him just a remnant of his remaining soul left of him, the real him died, when his soul was sent it merge with the full soul of trash young master, so all his peraonality (plus he ain't remember his past except cultivation) and what even worse he himself don't know that he don't remember, cuz the heroine alter his memory just so that he not being burden albeit he had died and just remnant soul, and for him to stay alive his cultivation teq still she keep them for him.....the reincarnated her don't know at all until she found the statue (via induction) and also after she get the her Vessel the treasure of her past life, she remember a bit, alas the mc (remnant soul that had fuses with full soul of of trash young master go Harem cuz his powerful cultivation)....Well I just remember a little I read it around 2015 or 2016 back then anyway