AnimeWeeb69

http://www.mangago.zone/read-manga/hirunaka_no_ryuusei/
http://www.mangago.zone/read-manga/unriped_expression/

just was about to recommend the second one lmao it's good

Everyone is complaining about Unripened expression ending but I was very okay with it actually xD It was what I expected

(And yeah, it's one of most famous yaoi with multiple love interest :D)

Some other love triangles:
http://www.mangago.zone/read-manga/wistful_summer/
http://www.mangago.zone/read-manga/love_or_hate_yeongha/

Love or Hate (it's the most stressful yaoi I've ever read)

Skip Beat (it's a shoujo, at first seems to be a love triangle but after it’s obvious who she gets at the end)

Blood bank

http://www.mangago.zone/read-manga/sakurada_senpai_kaizou_keikaku/

http://www.mangago.zone/read-manga/from_points_of_three/?av=2
the main story has it. but they're also a good few chapters on bdsm from 54-56

BDSM
list is a collection of
 • dom seme x sub uke
 • dom uke x sub seme
http://www.mangago.zone/home/mangalist/603799/

Follow the list to be updated. And if you liked the mangas/manhwas I included, please do recommend. Enjoy~ (人 •ᴗ•)