
(Spoilers below).
Yes, you are right, my friend(▰˘◡˘▰)...I've read the raws.
My prediction is Minato wrote a letter to Kaito and Nagisa before he died that Minato already had someone he loved and also Minato put his photograph where Minato with the guy. I'm sure it is not Nagisa's fault that Minato died. I guess Minato had his own reason about the guy. Maybe, Minato's parents didn't allow Minato to fall in love with a guy so he died. Then Minato's letter might have said that please let have Kaito and Nagisa a happy life.
This is not a love triangle. Kaito loves Nagisa deeply. Minato loved another guy who showed up in the photo where he was with Minato.
If My prediction is wrong, then I'm extremely sorry.#-.-)
Imagine what a plot twist if the seme actually liked nagisa from the start and not minato lol .. tho it's likely not the case