I was thinking this. I'd love to see that. This might be the only series where I'd be happy to see what the side couple is up to just as much as the main pair.
So many of you are so quick to just go "GUYS HE JUMPED SHIP" but I can almost guarantee you Kimiya'll never fall for a fucking landmine like Popochi. He's going there to tell her to lay the hell off so he can enjoy his time with Urumin in peace.
100% the other ending is a "happier ending" which doesn't actually end, they get married and we get a fluffy slice-of-life. MC gets a character reveal and we get to follow their story until the god who is Tsuniya-sensei dies.
It's good to know that all that wasn't for nothing. Though her way of thinking isn't completely right, I definitely understand it. Here's hoping he can convince her that his self-improvement doesn't mean the end of their relationship. This manga is about to get very, very good.