
Still hoping for the day where a healthy 3p relationship dynamic gets portrayed in bl :')
I've been thinking that I usually like 2nd couples better because they aren't so dramatic. Also, it's great that sunyool gets his happy ending <3

Try reading this one http://www.mangago.zone/read-manga/ai_to_makoto_moriyo/ Ai to Makoto (Moriyo) (Yaoi) manga its omegaverse, so its have its specifics, but its quite nice read.(≧∀≦)

http://www.mangago.zone/read-manga/choco_strawberry_vanilla/
I liked this one.

I was also hoping for poly initially, so I feel your pain. I think I've got every vaguely decent threesome manga bookmarked. Unfortunately, ambiguous threesomes are common, but full on poly tends to only be implied at best. But here are some links.
I Wanna Die Before I'm 30 (already mentioned, but not linked): https://www.ebookrenta.com/renta/sc/frm/item/140197/
Yupiteru ni Onegai: http://www.mangago.zone/read-manga/yupiteru_ni_onegai/
Stuck Between a Sexy Rock and a Hard Friend: https://www.ebookrenta.com/renta/sc/frm/item/138733/
Uchi wa Futago de Teppai! (kind of): https://myreadingmanga.info/kamiya-memo-uchi-wa-futago-de-teippai-eng/
And then some more that fit the bill, but which aren't faves:
Boys Love!: https://read.futekiya.com/comic/5d920d3f4c1ef
Mob Kei Danshi: http://www.mangago.zone/read-manga/mob_kei_danshi_no_yuuutsu/
Bokura no Nichijou no Mouhitotsu no Saundotorakku: https://myreadingmanga.info/bokura-no-nichijou-no-mouhitotsu-no-saundotorakku-eng/

The first time they met, the uke was smashed and the seme had his way with him regardless... And then he tried to play with his feelings which backfired on him cause the uke had recognized him. So I don't really get the sympathy for the seme in the comment section. Neither of them are really good people, they deserve each other.
However, after that being said, I really LOVED it and I'm hoping for a continuation. I haven't had enough of them.
the first movie covers till mid chapter 8.
2 more movies have been announced yet and without watching the first movie i can tell you i am not ready.
Saezuru Tori wa Habatakanai: Don't stay Gold is just an OVA that covers Kageyama and Kuga's first meeting. From what I've seen on Twitter we get the smut in the movie, which has a R18 rating.
oh my! I envy you for seeing the movie... Now it makes me too anxious to wait several months more!!! ╮( ̄▽ ̄)╭