They had sex on the trip in volume 7, they decided to live together and this ended up serving as a reason to reveal the relationship. There is nothing more to be explored here, it is an ending at the right time.
Slice of life doesn't have exciting endings like an action and drama would have.
You have to understand a big issue that romance manga have.
When the manga is about a couple trying to get together, people will be upset because they’re dodging actually getting together.
But if the couple
does get together, people will be upset if nothing else happens. Because you need to have some conflict, whether it’s the next step of the relationship or what have you.
It’s like a dog chasing a car. They don’t know what they’d do once they catch it.