Responses
https://www.mangago.zone/read-manga/datte_maou_sama_wa_kare_ga_kirai/ ( you might also want to check this one out fufufufufu (TRIGGER WARNING: r*pe)
Thank you so much for helping me find it, as well as for the recommendation!
The manga is a bl, in a world of demons with horns, but one of the last remaining humans is found out because of his lack of horns and starts a relationship with a demon
They are high schoolers I believe