Because many players don't like the idea of your long time crush begging money to fix her shitstain boyfriend's mistake, and now she's involved in deep shit thanks to her arrogance and stupidity.
Before you defend her actions as "realistic," swallowing your pride and guilt and confessing how your boyfriend splurge the money again to your best friend instead of ghosting him is also realistic.
If MC treats her right, she actually acts like a nympho. Just a food for thought.
Nicki is nothing unique, though she is admittedly the most interesting girl in the game so far.