2) rivals/ enemies
http://www.mangago.me/read-manga/versus_x_lovers/
http://www.mangago.me/read-manga/junketsu_drop/
http://www.mangago.me/read-manga/sailor_danshi/tr/97949/page/55/
http://www.mangago.me/read-manga/harenchi_no_susume/
http://www.mangago.me/read-manga/rival_ni_ki_wo_tsukero/
http://www.mangago.me/read-manga/aisaretaino/
http://www.mangago.me/read-manga/sunao_ni_narenai_otokotachi/
http://www.mangago.me/read-manga/like_the_barren_wasteland/
http://www.mangago.me/read-manga/parallel_lines/
http://www.mangago.me/read-manga/koi_wa_ichiya_ni_shite_narazu/
http://www.mangago.me/read-manga/koi_nante_shinai/
http://www.mangago.me/read-manga/chuuken_kunshu/mr/chuuken-kunshu/5/7/
http://www.mangago.me/read-manga/you_re_my_loveprize_in_viewfinder/
http://www.mangago.me/read-manga/renai_kyoutei_nukegake_nashi/
http://www.mangago.me/read-manga/kirai_kiraimo/
http://www.mangago.me/read-manga/black_sun/ ongoing
http://www.mangago.me/read-manga/kiken_na_otonarisan/
1) exes get back together
http://www.mangago.me/read-manga/priceless_honey/ chapter 2
http://www.mangago.me/read-manga/honoo_no_suna/ chapter 3
http://www.mangago.me/read-manga/konna_otoko_ni_dare_ga_shita/ chapter 1
puchitto hajiketa is exes getting back together
exes getting back together
http://www.mangago.me/read-manga/koakuma_no_sanctuary/ first story
Yaoi where 1) exes get back together or 2) two people who can't stand each other eventually get together in the end.