"Aye, but it seems that their queen is no more. Loras, Margaery and Mace Tyrell were among the victims of the fires in King's Landing. A good part of the Reach's nobility was present in the capital, including nearly thirty thousand swords. All perished in the fires. Now they have no female relatives left to tie into the southern Throne, and the shores of the Reach are under attack from the Ironborn. Euron Greyjoy is harrying their shores hard, so they are probably reluctant to send any help to Cersei. Hells, it's not even sure that most of their bannermen would follow them anymore. After all, House Tyrell lost a good amount of knights and troops in King's Landing," Jon said with a shrug.