Funny to watch until you get to EP30 where everything goes down a bad lane

The drama was so funny and nice to watch, but since ep 30, it started to go down the road in a such bad way… I don't understand how this script was accepted? How could they think this ending made sense??? It's so wrong, and such an ending is illogical. It happened fast and for no reason. I am so disappointed.
The cast was not bad at all during the drama, but I can't think about any reason that made them accept this ending. It feels like I wasted my time on this drama and it's so sad. It's the first time in many years of me watching a drama. So annoying!!!