Idk the exact manhwa so I'm listing some that I know have black haired seme and blonde uke. Hope it's one of these.
Can't Think Straight
https://www.mangago.zone/read-manga/crossing_the_line_1/
Pass, Nonpass
https://www.mangago.zone/read-manga/pass_nonpass/
Sunshine Shower
https://www.mangago.zone/read-manga/sunshine_shower/
Why Are You So Kind To Everyone Except Me?
https://www.mangago.zone/read-manga/why_are_you_so_kind_to_everyone_except_me/
Be, Be
https://www.mangago.zone/read-manga/be_be_1/
Focus on You
https://www.mangago.zone/read-manga/focus_on_you/
Muhyeok and Naui: My Irresistible Neighbor
https://www.mangago.zone/read-manga/muhyeok_x_naui/
Blaze Out
https://www.mangago.zone/read-manga/blaze_out/
December
https://www.mangago.zone/read-manga/december/
My Guildmate Next Door
https://www.mangago.zone/read-manga/my_guildmate_next_door_shortcut_scans/
OMG TY IT WAS DERAIL
does anyone know that one yaoi where the seme has black hair and the uke is blonde. They’re in college and it’s mutual pinning, they also room together. The black hair is kinda manipulative, he pretended to do it in their place even tho they promised they wouldn’t bring anyone over to do that. It shows the seme pov first and then the uke pov, where we find out he was also getting the seme to be jealous or like him or something . I just remember the uke having friends and the seme just likes staying by his side