Not sure which ones are unpopular but here’s my list of enemies to lovers romances.
https://www.mangago.zone/home/mangalist/2666041/
Haven’t really seen much of these so hopefully some of them are new to you, hope you enjoy~
https://www.mangago.zone/read-manga/ore_to_joushi_no_kakushikoto/
https://www.mangago.zone/read-manga/romanticer_s_high/
https://www.mangago.zone/read-manga/mihanada_pectolite/
https://www.mangago.zone/read-manga/tadareta_koi_ni_wa_itashimasen/
https://www.mangago.zone/read-manga/castle_mango/
https://www.mangago.zone/read-manga/this_question_is_super_difficult/
https://www.mangago.zone/read-manga/the_half_demon_dragon_knight_is_obsessed_with_the_markgraf/
https://www.mangago.zone/read-manga/peach_and_her_papas/
Unpopular enemies to lovers bl pls