Have you already read Nerd Project or Yang Il-woo and I? both aare pretty much about their relationship but the plot on both of them and just how dynamic it is WITHOUT being 30% plot and 100% smut is so good.
The Foul
Swapping
Rainbow City
Death Delayed by a Will
The Hunter Wants to Lay Low
If you haven't read this one
https://www.mangago.me/read-manga/trigger_yaoi/
Or if you enjoy a story with a baby on it https://www.mangago.me/read-manga/raising_a_child_and_falling_in_love/
These have a lot of tension, and a bit of a slow burn. Smart and strong MCs as well
https://www.mangago.me/read-manga/no_moral/
They dont shebangalang until like 80 chapters in. The art isnt less developed at the beginning but it doesnt take long at all until it starts getting better. I really love this so much
:: slowburn?? OMG I LOVE THIS QUESTIONNNN
https://www.mangago.me/home/mangalist/2502697/
:: you could recommend to a non BL reader ✎⋆.࿔*:･ ɢᴇɴᴇʀᴀʟ ᴀᴜᴅɪᴇɴᴄᴇ
https://www.mangago.me/home/mangalist/2488808/
:: we love commitment in stories ✎⋆.࿔*:･
https://www.mangago.me/home/mangalist/2475713/
like a bl, with an actually interesting plot (maybe doesn’t only involve the characters relationship) not too much smut or none at all, tension and long building