I think it's too early to speculate about the romance outcome but for now I'd stick to this: He chooses Moka, the other girls are sad but understand and respect that he had more feelings for her since they knew it all along anyway. To pacify the other girls fans the author could do something cheesy in the last chapter like introducing 3/4 male characters that suit each of them
(Incubus, Snowman etc... you get the idea).
A harem ending would be way out of place, he was all over Moka from the beginning, still possible - mangakas manage to suprise me with fucked up endings lately
