Game Of Thrones: 15 Plot Threads The Show Totally Abandoned
12. Nymeria's Wolf Pack
Nymeria was sent away in just the second episode of the show, with Arya scaring her off to spare her from execution. She eventually returned in Season 7, serving as a reminder to Arya of who she really is and helping turn her attention back home to Winterfell.
While Nymeria did fill a purpose then, it also left a huge wolf pack roaming around the Riverlands, which is something that George R.R. Martin himself has big plans for in the books (where tales of the pack have been much more commonplace).
There was half-an-expectation that we might see Nymeria again, with her and the pack perhaps coming to the aid of Arya and co during the Long Night, for example. But the show cuts the direwolves where possible, and opted against bringing them back, so presumably they're still just out there wandering free.