Keeping the e5-pawn is important in order to resist. This mistake ends the game.

The a4-pawn is in a very bad way and this is on top of the material deficit, so White chose to resign.

White has just played 30.h4? with the likely intention of continuing 31.g5 when he would gain a large space advantage and lasting pressure. This involves calculating a simple variation that gains an exchange for a pawn and evaluating the resulting position.

White has an exposed king, his rooks lack prospects and he has weak pawns on e3 and h4, or elsewhere in case of a modification of the structure. The black knight has excellent squares on e4 and f5 and the g4-pawn is annoying. Without calculating anything we can see that White cannot be better and is probably much worse. Thus, to have played 30.h4 in a superior position was a big strategic mistake.

Threatening a check on e4. 37...Ne4+? immediately is no good because of 38.Rxe4.

White gave up without asking to see 40.Rg2 Re3+ followed by mate.