That's quite the satisfactory ending, it was going to be Yuuna from start to finish.
And for those that wanted the harem ending... to be honest, the phrase seems to have developed into a metaphor for the relationships that we cultivate over the years, as opposed to a group of adoring women that you can pick and choose from. Can you honestly imagine MC being that kind of person?
Nope, and therefore he being married to Yuuna right at the end was the best way.