We don’t really know how much forgiveness the Night Elves have given the Horde. While more than half of the Horde leaders showed up to defend Amirdrassil, Tyrande didn’t talk with any of them, nor did any other Night Elf that we saw.
A Horde player can have worked with Tyrande and the Night Elves lot throughout the game, so there’s some suspension of disbelief imposed there on how Night Elves might view the Horde player in comparison to their feelings towards the Horde at large.
And very awkwardly Blizzard has not touched upon if hostilities have continued or not with the Night Elves’ ongoing attacks to push the Horde out of Splintertree Post and Warsong Lumbercamp as brought up by Exploring Kalimdor.