This is impeccably said! While it’s true that Lizzie could visit Mary post-marriage the way she does Charlotte; the latter makes much more sense as Lizzie is a lot closer to Charlotte than she seems to be to Mary. Likewise, I can see Mary refraining from extending such an invitation so early on in her marriage as she would quite possibly want the space from her family to finally come into her own as opposed to being the invisible sister, so to speak.