There isn't one. No matter your choices, Daichi's relationship with Rintaro will always end in tragedy. The only thing I want people to ask is "Why do things end like this?" Because by asking that question, they can enter the next arc to be released with an open mind and begin to dig deeper into the family's history to learn firsthand why this story has no happy ending.
Why giving the choice in 3 places then, if they all lead to different bad endings? The boy just wanted to be honest to himself and everyone and wanted some fun, cannot judge him for that. In fact, this story, at least its first part, resonates with mine a lot and I liked it. But when I realized that it leads to a tradegy no matter what you choose - it made me sad and angry. It sort of depressive.
The choices decide if you see the true or bad ends. There's a point system in-game. Get below a certain score and you get the bad end. And there's no issue in Daichi's desires. Its just that he became involved with the wrong person. I wish I could explain more, but we'd be entering spoiler territory in things that I have planned. Just...grin and bear the pain for now. Once all the arcs are out, it'll make sense why things ended the way they did and maybe you'll get that happy ending you want.