An epilogue, tying up loose ends, could have been made with a month or so.
But he's been dragging this on for years already; simply because he has no ideas on how to continue after FET.
After he runs out of random ideas for the slave epilogue, he's just gonna add more random scenes to the love route. Or the older books. Or add an epilogue to the epilogue. What happened after the wedding? Keep subscribing to find out.