These are all longer bls (some shounen ai, others are yaoi)
mo dao zu shi/grandmaster of demonic cultivation
unbreakable master
define the relationship
Full Moon Alchemist
Punch Drunk Love
My Guildmate Next Door
Hotel Phryne
payback
Murderer Llewellyn's enchanting dinner invitation
Rebirth
A Painter Behind the Curtain
Blood link
Assorted wilderness/Madman combo
Approximal guide
Hell & high water (its a novel series and only the first book was adapted into a manhwa, but i recommend reading the others too)
To be or not to be
Two souls
Bad friend/frienemies:thicker than blood
Dark guardian (not that long)
Nidome ha Shoujiki (this one is shorter)
Also havent read crazy obsession
Not Blossom (plot basically finding out who killed Yukio and MC is main suspect not that complex but rlly good read)
Hotel Phryne (MC has to find out who his real crush is after his crush got cloned and now there's like 10 people claiming they're the real uke)
something with a really good plot
(I heard cozy obsession has good plot)