Hello monster and School 2013 were definitions of Bromance <3
I agree, that group friendship is something different but in "Shut up" I see it as ML & dead guy (forgot names but they both are great) bromance and Reply 1988 is amazing as drama. I also don't love when friendship (which is in every drama), which doesn't make you fill emotional, is listed as Bromance.
except already listed, emotional deep Bromance which comes first in mind is The King in Love if you watch historicals too. it's really amazing and beautiful drama, great acting and cinematography, great emotional romance and amazing bromance, where one is ready to sacrifice himself for another, bond is soo deep that he feels like another.
Same deep connection and loving another so much to sacrifice himself is Cruel City and also mind blowing , great drama, it's really must watch, there are maybe 2-3 dramas like this, unpredictable, without cliche and perfect in every aspect.
also different and good drama Save Me there is bromance, good one, but not on the level of Hello monster, School 2013, Cruel City or King in love.
The Great Seducer - is very deep and even strange friendship between 2 boys and 1 girl, bromance between boys, then other girl (FL) comes and kind of ruins this group. this drama has something different and interesting, modern story of "cruel intentions" with Gossip Girl vibe.
Moorim School isn't great as drama, but good cast, bromance is on/off, enemies/friends kind
Lucifer as for drama it was great, emotional, very unusual, great romance (not standart, but good girl loves bad boy even though she knows he is bad). Bromance is also unusual, most of the show they are enemies, but this complex relationship develops to understanding to each other and even respect and at the and you can say it's bromance (not happy ending)