
All're because of the genius of mangaka. I think many fan of One Shot readers got that as well. You just don't get used to specific style of One Shot.
http://www.mangago.zone/read-manga/eiyuu_to_shounen/ - This one is just like a long series of sweet romance to me.
http://www.mangago.zone/read-manga/ai_no_marking/ - This one is only 5 pages

Yeah sensei alway doing great making a genius plot which unexpectly hurt to kokoro. So my conclusion was right about they could be died together. But when i realized your answer about having silent just because he want to get along with his attendant , its really break my heart into a piece. I wanna cry too, but its late
Tremendous Art!! .•✿✿•. Heartbreaking Tragedy!! (ಥ_ಥ)
The King's love is too great to word! If he revealed the truth once he found out, they would not be able to stay together, so he preferred to keep quiet and let the attendant poisoned him. Even in the last moment, instead of shooting the servant, he handed him the gun. I can't imagine how much it's hurt seeing his beloved fed him the poison during these several years. ARKKKK... I wanna cry my eyes out. (ಥ_ಥ)
The King killed him with his love, not the gun!!! «••»
After realized how much the king loved him, compared to what he had done, even the king didn't ask him to go together, I still believe the attendant would definitely commit suicide.