I think you have to read this from another angle.
This book setting is in this part of the town that's free and easy especially when it comes to sex or relationship. Daiki is in the shop because he is intrigued with Miharu but he wasn't necessarily in love with Miharu, at first. You can see he is supportive of what Miharu is doing with this personal life. They're not even committed to each other until chapter 8 ish.
We all can see Miharu is a free soul, before or after Daiki. And I love that this manga show that, with Daiki being there and supportive of his lifestyle until Miharu choose to do otherwise.
So this book is the essence of Miharu who is lost in life, wandering around looking for love, wayward as it may be, he know Daiki adores him but is it love?, to finally found love.
This book is more about Miharu than Daiki tbh. I didn't read this manga for Daiki or anything, mostly just enjoyed the freedom for Miharu choice to do what he wants, help the customers the way he know how and Daiki being supportive until the end.
Daiki deserved so much better. What the hell was that relationship development? Miharu spends the entire manga neglecting and ignoring Daiki, but then decides to completely turn around and confess his "love" for Daiki? Ew. No way. Daiki deserves someone who actually gives a shit about him, not someone who goes around fucking every stray dog just to say "omggggg I love you" when none of their other one night stands work out