Any merits to this theory about why GRRM is taking so long on “Winds of Winter”?

Hello all, just started reading book 1 of the series and I’ve watched all the shows + keeping up with all the side shows (Ko7K & HotD).

I don’t know how to feel about investing in a book series that may never be completed (especially since I’ve also watched the shows).

But I’ve heard that the reason why GRRM is taking so long is that the end of the GoT series, although it wasn’t based on a book was close to how GRRM wanted it to end with his consultation- and that the backlash of the series ending has now put GRRM in a bind since he’s now trying to come up with a different ending altogether knowing fans hated the one presented through the shows? Any truth to any of this?