I know people are hating on this because a “perfectly good ending” was ruined, but it can be appreciated as well. In a way, it’s refreshing to see some realistic future setting to show that not all stories end happily. It seemed that way, but in reality, people don’t get that fairytale ending and sometime shit gets even worse after marriage. Like you mentioned, the grandpa thing wasn’t resolved and this is the outcome. It feels like the author was probably trying to convey something along the lines of “unfinished business” or not “tying up loose ends”. While we thought the ending would be a happy one, theres a looming evil waiting to ruin this “perfectly good story”. Kind of like a calm before the storm type.
Though I gotta admit the timing is random lol it would make sense if this started right after the final season, but it came out years later, so maybe that’s more of why people are mad haha

Lol, just wanted to say this. I knew this would come back worse, cos they never resolved the grandpa issues in the previous season