I relate to her insofar as I'm also biracial with more of a white phenotype. But based on my own experience w/people's reactions, she's wrong ... black people understand what they're saying when they tell her she "doesn't understand the black struggle". She probably has no basis for whining about that. We don't understand - not the way mono-racially, or mostly black, people understand that black struggle on the daily. Whether she sees it or not, I highly, highly doubt ppl who look like her (or me) get the same level of BS from whites. I have half-sibs who are fully black. A cop pulls them over just for being black, just for being "brown". If I'm going twice the speed limit in a school crossing zone, I don't get pulled over, or if I get pulled over I fake a tear and the officer falls all over himself to make sure I'm OK, then let's me go w/a warning to feel better.
At the same time, I do acknowledge that people like her/me do have our own unique struggles that can't be fully grasped by any mono-racial group. That said, our struggle is different, not harder, than mono-racial black people IMO. Definitely not harder IMO, and probably much easier, the whiter the person is or looks. And yeah, like her, there are times when I've felt on the outskirts of various racial groups. That is a PIA sometimes. Humans all struggle somehow though. ... But anyway, she would do well to feel a sense of pride in her hair, whatever anyone of any group says about it. Just choose folks from all backgrounds that don't bash your hair lol