He wanted a white girl.

I don't know what he sees in her either. Aside from the obvious that she just looks gross - I could smell the oily hair through my screen - in reality Nicole would he a quick bang at best.
Nicole getting him in trouble would have been the beginning and the end for a guy like Carlos. Even if he decided to see her again after that it wouldn't have gotten to the point where he would start seriously slipping. Someone that works that hard would never jeopardize their future for a screwed up slut. When she didn't care to use a condom with Carlos the first thing on my mind would be that she must not care to wear one with anybody. In a nutshell their "deep" relationship just wasn't realistic at all - total bullshyt.

That's why the movie is called: Crazy/beautiful. He's the beautiful she the crazy.

That wasn't grunge, that was filthy and gross.
She was miscast, he was prettier than she was.
I get she is supposed to be "troubled", but her hair was disgusting. Given her background someone would have washed that mess even if it meant holding her head under the sink.
Wasn't realistic.

Thanks for the explanation I have wondered as well what he saw in her.

Although this movie came out in 2001-Grunge was a thing a few years earlier.
A lot of people I knew who had $$$$ dressed this way. Thrift store chic if you will.
Its a form a rebelling same people are now Brooks Brothers/Vineyard Vine just like their parents. She would've grown out of it (and him) too.
“Shoot for the moon. Even if you miss, you'll land among the stars.”

I agree, she did look like a raggamuffin. But on the other hand. He was a child and was drawn to her because she seemed so carefree.
"Do you even remember what you came here to find?"

Agreed