Oikawa was going through some things, prolly internalized homophobia, Hinata was right there, there was tension, there was Hinata and kageyama's decently open relationship, they were grown adults, and oihina forked in Brazil. I think it was a matter of Hinata and oikawa were into each other just enough for the tension to be palpable, and sho was able to help oikawa come to terms with being fruity, and I feel like while they were adults having fun and being kinda stupid, shoyo also at some point was like "hey oikawa, you're gay my dude" and kinda helped oikawa work through feeling cuz sho is a good person and shi. anyways oihina forked in brazil, thank you for coming to my ted talk. or a bokuto would say, liszto talk. (I KNOW WHO YOU ARE)