I don’t think Miho needs a reason to accept her boyfriend sleeping with others. This whole thing with Nao and Miho is clearly a polyamory relationship and that’s perfectly normal. Society doesn’t technically accept it, but monogamy isn’t the only kind of relationship that exists in this world. As long as all parties involved consent to it, then it’s a completely ethical polyamorous involvement.
Ah no that I got. It’s not really the poly thing - I mean to be honest I don’t get that either but it’s not my business and therefore if it works for them it’s okay - it’s more the fact that nao slept with someone that has feelings for him. And I’m pretty sure miho knew that as she strikes me as someone who’s very perceptive. Even if you’re poly wouldn’t that be a bit uncomfortable knowing someone that has feelings for the person you love sleeps with them ?

Idk i just don’t like this story as much as I wanted to. The neighbor guys boyfriend kinda deserves more than a boyfriend that tests him like that. Also the whole arrangement between them is kinda messy, it’s cleared up but still. I can’t seem to understand how miho has no problem that her boyfriend slept with someone that had a crush on him... I do like Chika and ryo together in the end but idk the things before could have been handled better than that