Responses
In Japan, that's how gay couple get married, so it's probably that way in South Korea too.
No, seme didn't love his step brother romantically. His step brother was very dear to him as family, which is understandable since his parents are like that. So he felt really guilty since his rejection drove his step brother to commit suicide.

Soooo you can adopt an adult? I imagine since gay marriage isn't legal, this was the seme's workaround with the family biz... but is adopting adults a thing?
- Did the seme have feeling for his step bro? I couldn't tell if he just loved him or was actually in love with him too.
- What's the deal with Spencer? His character felt really off to me...like he had a few screws loose? Was he just really spoiled?