@mommunism
Now we're diving into the realm of opinion, friend, and that's where we have to draw a line. Outside that, I already stated that most of those endings are done in drama. When they are done in comedy, it's to allow a small form of realism as most countries, namely Japan, don't jive with polygamy. Most of them usually end open anyways despite the choice of one. As the other girls typically, like I said before, contest the choice. Or it ends before the choice is made.
And, To-Love Ru was done open ended to allow for its continuations. Like a movie setting up sequels. Again, it being "a shit ending" is opinion.
Going back to this story, most of the girls are ok with the polygamy. Papi wouldnt get him choosing someone else. She's said before, in the beginning, she doesn't understand the idea of "husband" being someone else's. The only two with any sort of issue is Centorea and Miia. But reguardless, it'll end open regardless of his choice. That's the type of story and those are the type of girls. But, again, this is opinion.