See, here Usagi admits she knows she’s being irrational and she understands that Mamoru would feel protective of his child, she’s just very jealous that she has to share him and she’s jealous he has a bond with someone that’s different than his bond with her but equally intense, and a bond she can’t be a part of.

She just can’t handle these adult feelings at her young age. (Have to love Mamoru’s dramatic posing here though)

In the anime, any serious jealousy from Usagi dies after the parental reveal, and any fighting over Mamoru is mostly just Usagi being silly and playing around and looking for a fight with Chibiusa while Chibiusa goes out of her way to annoy her, and just some continued mild jealousy over the fact she has to share Mamoru, but nothing as intense or deep as what’s depicted here.

Okay, I’ll stop for now, and in a while I’ll spam some more manga where we’ll examine Chibiusa’s backstory and relationship with her mother and her side of the Mamoru-lovin’ equation, and see Usagi sort out her feelings as she develops an equally strong bond with her daughter as the one Mamoru has with her right now. Also, Mako explains everything from Mamoru’s side for us because she’s cool  and insightful like that, and GOD, you can’t expect Mamoru to talk about his feelings HIMSELF!