Side couple in love is an illusion
https://www.mangago.me/read-manga/oblivious_mr_b/
It's kinda psychological but worth to read-
https://www.mangago.me/read-manga/sex_lies_bussy_wrap_a_hunt_for_the_omega_slayer/
Side couple in this too
https://www.mangago.me/read-manga/kashikomarimashita_destiny/
AlphaxBeta recs pls (=・ω・=)