Responses
Behind the Scenes
Love or Hate (I think this somehow fits tho I think he didn't cheat totally since they don't have a label ╮(￣▽￣)╭)
http://www.mangago.zone/read-manga/sing_on_the_water/
http://www.mangago.zone/read-manga/he_him_us/?Nlbl
http://www.mangago.zone/read-manga/trap_city/
http://www.mangago.zone/read-manga/the_god_of_pain_s_groom/
http://www.mangago.zone/read-manga/hate_mate/?0Myw
http://www.mangago.zone/read-manga/swallow_gawee/
Can you recommend some heartbreaking yaoi where the seme cheats? But the uke will find someone else eventually.