Ane no Tomodachi - Ch. 26

[dbzclamp]

She's also not stopping the romance from happening.

Unless you count her deliberately crashing their aquarium date.

She's pretentious and condescending because she's an author stand-in without any humanizing flaws. And every time tension from an interaction between Hina and Asahi--be it awkward tension or otherwise--she's there to be Hina's crutch and the cycle resets.

I'm going to add that the other characters are constantly telling the reader how amazing and beautiful and cool she is. That's incredibly off-putting to me, especially when she acts exactly like how you described.