Ah yes, she's getting jealous someone will try to take away her girlfriend, completely a friendship issue, totally platonic, very ✨️demure✨️ like young people say.
(But seriously tho, I hope that now that she came out of her shell we finally get real romantic relationship progress. I know some people are fine with them getting the "implied-only" treatment like in certain sports animes, but I came here for the cute couple, not for some glances that I have to do some mental gymnastics in order to say "Hmm yes you see in this panel she looked at her in a certain way that implies she likes her and when she gave her that roll of toilet paper the author implied she was confessing because the paper sleeve had a blue zigzag pattern which in T.P. gifting language means that they're confessing").