On the story "The Grasshopper", Monika says "I love you so much, [player]~", but there's no "I love you too." afterwards.

From what I see there appears to be "I Love you too" dialogue...
There is supposed to be an "I love you too!" coming from the player, not Monika. When you tell her "I love you too" she just reacts, not a "I love you too!" from her since you already said it.
Oh, alright. Sorry about that. I think I never looked into history so I have like zero idea about how it should look. But yeah, she just closes her eyes, blushes and smiles sweetly.
I can't replicate this, seeing the story myself, I get the I love you too option
Wait, was this from a new story or via asking her to tell you this specific story?
I used Can you tell me a story? > New story.
Okay I see the issue
This is addressed in the linked PR