Ending wasn't enough to actually end this series
. In some ways this is the kind of thing I fear with series I like. Just perpetual milking beyond any reason to keep the story going.
If they wanted to tell another story with the main couple I wouldn't actually say that's a bad move. But leave the harem behind in that case. In some ways it is just downright sad for the other girls. Just have them take the loss and move with their lives. Hanging around for their sister's honeymoon is just bizarre.
In the end, money talks. And they probably can get away with milking this thing even more before the most hardcore fans start getting annoyed.