Hyperventilation ?
hyperventilation! theres also an anime, its linked in my fluffy whole some shit list
i thought it was hyperventilation too so i read it but it's not... i remember the crush being late to the reunion because the first scene was just the main character and a few friends sitting in a restaurant waiting for the crush to come and i don't think there are any sex scenes..
idk then, it sounds the exact same as hyperventilation tbh
i'm pretty sure it's a short, colourised BL manhwa. it's a reunion and the main character attended the reunion only because of his childhood/school crush (or best friend?) was going to be there, and his friends know this and complains about it like "you only came because u heard this other person is coming" and the story ends with him and his crush kissing in front of the restaurant bathroom. the crush was late to the reunion because he moved overseas and just returned back.