Do you mind if they break up and reconcile afterwards? Or are you looking for those break up and that's the end of their relationship? Here's a mix of those two types (so you won't get a spoiler ;)) :
http://www.mangago.zone/read-manga/tatoeba_konna_koi_no_hanashi/
http://www.mangago.zone/read-manga/escape_journey/
http://www.mangago.zone/read-manga/momentum_park_ji_yeon/?av=1
http://www.mangago.zone/read-manga/back_in_time_to_you/
http://www.mangago.zone/read-manga/life_senjou_no_bokura/
http://www.mangago.zone/read-manga/let_dai/
http://www.mangago.zone/read-manga/doushitemo_furetakunai/
http://www.mangago.zone/read-manga/sojou_no_koi_wa_nido_haneru/ (has a prequel Kyuuso Ha Cheese no Yume Omiru)
A yaoi manga(s) where it doesnt work out between the two of them, they breakup etc.