Romance with good character development

🔸 (somewhat) Well-written story
🔸 Story and relationship will lead somewhere (not sad ending)
🔸 Not 'too shoujo', but shoujo is ok
🔸 Story and 'romantic' development feels natural/realistic

I'm ok with BL/GL too

Any: Anime/manga/manhw(u)a, etc. no LN for now

If you don't mind fantasy-romance recommendations, I suggest Cardcaptor Sakura and Prétear: The New Legend of Snow White.

CCS anime - https://myanimelist.net/anime/232/Cardcaptor_Sakura
CCS manga - https://myanimelist.net/manga/106/Cardcaptor_Sakura
Prétear anime - https://myanimelist.net/anime/100/Shin_Shirayuki-hime_Densetsu_Pr%C3%A9tear
Prétear manga - https://myanimelist.net/manga/1248/Shin_Shirayuki-hime_Densetsu_Pretear

I prefer the original manga for both of these series, but the anime adaptations are actually decent, so take your pick.

I think Lovely Complex & Rainbow Days might be okay.
They're both lighthearted & funny, with a nice story.

Here are some romance stories that I think have great character development :

Ao no Flag
Yagate Kimi ni Naru
A Good Day to Be a Dog
My ID Is Gangnam Beauty

White Album 2
Akagami no Shirayukihime

Taiyou no Ie - Age gap, childhood friends shoujo romance with good sexual tension and well-rounded characters.

Kimi wa Pet - Age gap josei romance where the woman is the older party. If you don't mind love triangles, it's a great story about figuring out what really makes a happy relationship.

Cat Street - A shoujo about a former child actress who's now a shut-in finding an alternative high school for misfits and prodigies where she makes friends and re-learns how to be human.

Akatsuki no Yona - If fantasy historical anime/manga works for you, this has smoldering sexual tension and a heroine who grows from spoiled princess to hardened guerrilla, basically. Manga's still ongoing.

You have with Tsuki ga Kirei one of the best ones on-hold.

Just Because

I suggest Nodame Cantabile

As most people recommend anime I'll give you some manga options

Bitter Virgin - quite a short story about trauma, unwanted pregnancy and romance of seemingly 2 completely different teenagers
Nozoki Ana - I can recommend this one only if you don't mind a ton of sexual stuff, but underneath that is a very good story, not one-dimensional characters and interesting development
Taishou Otome Otogibanashi - based in early 20th century, heartwarming with great character development
Bonnouji - no unneeded drama, just a wholesome daily life of 2 people with too much interesting stuff in their apartment

Seishun Buta Yarou wa Bunny Girl Senpai no Yume wo Minai
Araburu Kisetsu no Otome-domo yo.
Toradora!

Full Moon Wo Sagashite

Fruits Basket (the new one is better)

To tell you the truth I can't actually write so many anime names
I know bunch of romance anime
So if you're interested in that then visit my completed anime section😊

- Akatsuki no Yona
- Akage no Anne
- Ao Haru Ride
- Fruits Basket
- Haikara-san ga Tooru
- Itsudatte Bokura no Koi wa 10 cm Datta
- Kamisama Hajimemashita
- Karakai Jouzu no Takagi-san
- Kareshi Kanojo no Jijou
- Kaze no Naka no Shoujo: Kinpatsu no Jeanie
- Kimi ni Todoke
- Kodomo no Omocha
- Lovely★Complex
- Mizuiro Jidai
- Sukitte Ii na yo