I think he romantically loves neither, beom is more convenient because he doesn’t understand human emotions he just wants geonpil to himself and can accept him fully
The hyung was selfish, wanted something out of geonpil and geonpil was ready to comply and give it to him but the hyung kept getting greedier to the point where he went to a shaman to make geonpil "fall inlove"with him through unethical means aka fforcing him)
but geonpil liked him as family, but didn’t mind having sex if it meant he can keep his place beside him (I think it’s linked to trauma and how he’s desperate for a place to belong)
Although I feel like he acts more affectionate towards beom ,idk if that can be considered "romantic" but it’s obvious what he feels for beom is better than what he feels for the hyung where he’s never comfortable with himself and constantly feels guilt,
and even if geonpil is "shitty" or a selfish loser like u said ,i don’t think beom even cares abt that in the slightest cuz again he’s not human ,he just wants geonpil regardless if geonpil is his lover of not,Unlike the hyung
It’s not a romance story it’s more like 2 lonely ppl who found comfort in each other and can’t lose each other
The hyung is..just there
I don’t think he’s needed in the story at all,he’s just there to make it messy
Everyone is this story is kind of selfish

Geonpil neved loved Hyung. He only loved his company and fulfilled his sexual urges with him. The person he loves is Beom. And I feel bad for Hyung amd Beom because they both deserve better than a selfish loser