
This is already the 2nd time Leo has heard about the arranged marriage thing. He should just get up and leave like he did before, and let Mikoshiba be the one to put in the effort to win him back. He's known that Leo likes him since they were younger, and he’s just hurting him even more now that they’ve slept together.
I agree with the comments. This doesn't feel like old-man yaoi with how immature they are acting.

My favorite ship is Kaede (elder brother) and Shinya (his best friend). Kaede's oshi looks like Shinya, haha. Same one tuft of hair in the middle:
https://www.mangago.zone/read-manga/fudanshi_kazoku/uu/mpn_chapter-2505494/pg-5/
His father's oshi also looks like his co-worker (Hiiragi). They all have a BL partner.
Father x co-worker
Younger brother x classmate (Shinya's brother)
Elder brother x best friend/childhood friend
Also Kaede's two friends
It's sad that this has ended already before we see more of those ships develop.

I just reread this today, and it always makes me happy. The artist did a great job of adapting our 2 MCs’ comedic thoughts into her drawings. If you have experience with RPS (real-person shipping), you’ll understand and enjoy it even more. Especially shipping Chinese BL actors, haha. I have followed 2 pairs. Just do it respectfully and in moderation.
The story’s got a good premise, just not well executed.