Does anyone know any BLs where the seme treats the uke like trash and then ends up regrett...

https://www.mangago.zone/read-manga/10_years_where_i_loved_you_the_most/

https://www.mangago.zone/read-manga/bbanana_scandal/

the 2nd couple fits your description and their story starts from chapter 65.2, but you could also try reading from the start since the 1st couple are also worth to see (⌒▽⌒)

https://www.mangago.zone/read-manga/black_lotus/

https://www.mangago.zone/read-manga/hina_wa_mitsuiro_no_koi_ni_torawareru/
Try this too

Second Banana Scandal s2. I would still read s1, but totally dif plot. You meet the characters in s1.

Thank you all!