>>122047529Your comparing apples to oranges.
Sprig's story is about him as a young kid helping his friend get home. Problems that he has are of a different nature, because Sprig is in its home turf. His interactions with other frogs are about that. It being his home turf. His development with Ivy is part of that. It's what frogs do.
Anne is on a mission to get her friends and get home. Romantic development isn't part of that. It's about Anne, her search for her friends, and her interaction with the world as they find their way home. Her story isn't about some internal struggle to find herself because she has no problems with who she is.
Ultimately the only reason any romance could work with the human girls is if it serves as a string for trouble, which a relationship between anne and marcy won't cause unless it's unrequited and Anne makes it weird.
That would also be bad though, because it makes the viewers dislike the main character.