You return her hug, and start rocking her side to side slowly when her sobbing resumes. Up on her hind legs like this, she’s a bit taller than you, despite being only about five feet on all fours. She’s actually the perfect height to be hugging a pony like this, you realize. Twilight can’t hug you around your neck unless you’re crouching or kneeling – though she has plenty of room when you’re that low – and Celestia’s weight with height-enabled leverage would knock you over; even the palace’s smaller rooms are so much taller than normal because her horn would lodge in the ceiling of a usual eight or nine foot clearance of a typical domestic floorplan if she reared back.