https://www.mangago.zone/read-manga/the_world_without_you/ (seme grows more crazy by each chapter; the chasing arc is insanely worth reading.)
https://www.mangago.zone/read-manga/unprecedented/ (unique character design ; obsessed & does whatever the uke says)
https://www.mangago.zone/read-manga/please_pay_attention_to_me/ (you mentioned shounen ai. it’s up to interpretation as to who the seme/uke is. black haired is very clingy and the blonde eventually becomes obsessed with him because he practically worships him.)
A Link Between Relationships
https://www.mangago.zone/read-manga/a_link_between_relationships/
Love Jinx
https://www.mangago.zone/read-manga/love_jinx/
December
https://www.mangago.zone/read-manga/december/
Lookin for a possessive seme!! Bonus points if he isn't nonchalant and actively worships the uke (≧∀≦) It can be short or ongoing idrm and shounen ai or freaky but I preferably like smut widdit... ⁄(⁄ ⁄·⁄ω⁄·⁄ ⁄)⁄ thank yewww