*Disclaimer: I love Nicki & she's probably my favorite LI*
I think you're forgetting the main sticking point for people. The amount she asked for and how little it is compared to Guy's total wealth is irrelevant. It's not that she asked Guy for money, it's how she asked him. In hindsight, her intentions were good and she made an error in judgement. However, Guy isn't a mind reader and her motives seem suspect.
From Nicki's perspective, she feels terrible asking a friend for a huge (to her) loan, but genuinely needs to. The whole evening she's considering and reconsidering how to do it while also spending time with a friend she's sorely missed. Before she knows it the night is over so she grits her teeth and rips the band-aid off.
From Guy's perspective, he suddenly came into money and tried to hide it to prevent people begging for handouts. Then, almost as he feared, a seemingly close friend tracked him down and showed up asking for money. If she had been upfront about it, it would seem more genuine. By spending the whole evening and asking before hitting the door makes it seem manipulative. Like she was guilting him into helping her.
Later:
Again from Nicki's perspective, things go to hell so she tries to not take advantage of her friend again by trying to fix things on her own. Too late discovering she couldn't contact Guy if she wanted to. Things get worse and without options, realizing who's within reach and despite feeling like she took advantage of him last time, she turns to the only person she thinks will help her.
From Guy's perspective, his fears have been justified. She showed up out of nowhere, pumped him for cash, then cut off all communication. Now here she is months later back on his doorstep with another sob story. It seems like she only contacts Guy when she needs something.
I admit, I didn't want anything to do with Nicki after this either... at first. However this does make her character more tragic and sympathetic as her story unfolds. By trying not to take advantage of Guy, it appears as if she's taking advantage of him. After the initial anger cools off, it makes me care for her even more.