Acid town
http://www.mangago.zone/read-manga/sakura_gari/ (just yes)
http://www.mangago.zone/read-manga/let_dai/ (shounen ai/a tragedy with a happy ending/just amazing)
http://www.mangago.zone/read-manga/not_equal/ (well the relationship is the main focus but not the only one and its really interesting)
https://tapas.io/episode/599071 (ongoing/psychological)
http://www.mangago.zone/read-manga/my_god/ (unexpectedly interesting)
http://www.mangago.zone/read-manga/tamayura_yuki_ringo/ (hmm the relationship may be the main focus but this is just beautiful)
oh i almost forgot: http://www.mangago.zone/read-manga/deadlock/ has an amazing plotline but its not finished :'( and if you are into gore you can also try: https://tapas.io/episode/467811 (but its more fked up than killing stalking so i dont know if u r gonna like it)
Vassalord, but it's shounen-ai.
please recommend me some good yaoi mangas with a good and intriguing plotline where the relationship isn't the main focus