I'd say it's shapping up to be the latter i.e. AVN where you choose one love interest. There will be different endings per love interest and you can stop pursing a love interest for some different types on endings but it's not a harem. Just a side note I don't have anything against harem games, and I've actually considered this a lot for this game, but I came to the conclusion that with its theming it just didn't make sense for it to be a harem.