Usagi is angry Chibs could think she wasn’t going to miss her, OF COURSE I AM, EVEN IF I SAY OTHERWISE IN A VAIN ATTEMPT TO STAVE OFF MY FEELS HOW COULD YOU EVER THINK I WOULDN’T IT SHOULD BE OBVIOUS.
For additional heartbreaking- Chibs immediately apologizing when Usagi lashes out even though she probably doesn’t know what she’s apologizing for, she’s still insecure enough that she feels she probably did something wrong.
And then we find out Usagi’s snappiness here comes from being angry at Chibs for leaving. YOU COME HERE, YOU MAKE ME LOVE YOU, AND THEN YOU LEAVE? HOW DARE.
If there’s one thing Usagi is bad at handling, it’s the idea of people leaving her, as we’ve seen repeatedly through this play. But what a twist- while before her heart was aching about the possibility of people leaving her BECAUSE of Chibiusa, now she can’t handle the thought of Chibiusa leaving. Chibiusa is now an essential part of her life, and her leaving is as painful and unthinkable as Mamoru, the girls, anyone leaving.
Usagi is childish, but her love is boundless- she loves her people so dearly that her despair at the thought of parting from them leads her to boil over. It was the cause of her problems with Chibiusa, but now it’s become the reason Chibiusa’s parting is a dagger.