Henry is anxious.

Alex wants a moment alone with him. Henry is sure he's about to get cussed out in the White House's red room, at the dinner party he was supposed to attend.

Henry does regret kissing Alex at the New Years party, then not explaining a thing and not speaking to him for a month. Henry was drunk, anxious, and he couldn't help but kiss the man he couldn't have. Which is why he's already apologizing once he lays his eyes on Alex in the red room.