Overdose
I just try to gather the similar plot which gives off the same vibes. Most are like they broke up or Seme treats Uke bad. Then the Seme wanna come back but the Uke chooses the new guy.
http://www.mangago.zone/read-manga/usotsuki_na_kimi_no_toriko/
http://www.mangago.zone/read-manga/suki_toiunoni_nazekashira/
http://www.mangago.zone/read-manga/our_previous_existence_this_world_you_and_me/
http://www.mangago.zone/read-manga/3_manen_no_kareshi/
http://www.mangago.zone/read-manga/koi_wa_koi_o_shiru/
http://www.mangago.zone/read-manga/35_do_no_ren_ai_netsu/
http://www.mangago.zone/read-manga/mind_flow/tr/86439/page/
http://www.mangago.zone/read-manga/chikan_diary/mr/chikan-diary/3/
omg thank you so much~!
My pleasure Missy-chan~ (◠‿◠✿)
Any yaoi manga with seme left uke, seme regretted it and went back to the uke, but the uke had someone already. Happy ending though plz~!