Why Tyrion's Reaction To Jon & Daenerys Was So Disappointing

Last night's Game of Thrones season finale, "The Dragon and the Wolf," delivered on the much awaited Jon and Daenerys sex scene. Obviously, there is a lot to unpack about that particular event, the minor point of incest being just one element, but I want to talk about a less obvious aspect. Namely, what the hell was going on with Tyrion? How long was he standing outside that bedroom? And why? According to Joanna Robinson over at Vanity Fair, there could be a valid reason for Tyrion's reaction to...