And upper level my ass, the moment she gets into the ship, people wants to fuck her, not kill her. She even uses her sex magic skill to get into my quarters by fooling the enforcers.
Yeah, having random people propose to have sex with you, especially when you consider them lesser evolved beings which would basically equate to beastiality, really is a good thing isn't it? No to mention, it was a singular person, not "people". She's being eyed maliciously by many people, from the Inquisitors you meet, to random nobles, and NPCs who take note of her. The last part is just flat-out idiocy, considering how she feels about even touching a human being.
This is not to mention the time at Janus, where she's literally treated as a mutant and left served as a bodyguard.
And that's a good thing? It's the only reason she's still alive, the fact they are not educated enough to know she's a Xenos. You are being handed the skull of her predecessor, considered a nice trophy to bring out at dinner.
Her kind is being kept in cages to shock or kill for pleasure on Footfall (they don't know they're fake Eldar), and you even have Drukhari and other Xenos in a cage at your RT ceremony on Dargonus. One of your noble houses openly hunts them across the Expanse, so do both your fellow Rogue Traders, and your own predecessor helped destroy a Craftworld, killing billions. Yeah, Humanity truly is being very nice to the Eldar.
Not saying they're not massive cunts, but relations between Eldar and Humanity have always been incredibly fickle, and in most cases entirely hostile. Largely because Humanity has grown to become so incredibly xenophobic, to the point where they kill their own just because they look different due to slight mutations. The Aeldari are an opportunistic race and will happily kill humans if it serves their purpose, but unless they are overcome by Khaine's lust for violence and bloodshed, they are not an inherently aggressive race. Humanity sure as fuck is, and only the nids out-do humanity in terms of how much of a cancer the human race is to the galaxy as a whole.
Yrliet has all the reason to despise every human she encounters, which is something every Eldar child is being taught from the very start, and it's entirely in-character and lore-appropriate for her to act the way she does. It's one of the few things Owlcat did pretty well with this game, getting the setting and character motivations right.