Ruyi often doesn't bother to debate and defend herself because as far as she's concerned, the moment when Qianlong turned into this impersonal arbiter of harem affairs, she's already lost. It doesn't matter which side this new Qianlong lands on, she's already grieving the loss of her childhood best friend and confidant who treated her as an equal life partner instead of the weird consort-subject dynamic that harem women are expected to fulfil.
I think for a while she really tried. She's seen Qianlong disappointed by Langhua, Gao Xiyue and to a lesser extent Consort Chun so she empathises that he is in a tough spot where he can't really trust anyone, so she tries to make things easier by earnestly proving to him that she was the loyal partner she had always been. What I think really hurt her is how little Qianlong regarded what they once had. Before everything came crashing down, Qianlong rarely looked back wistfully at what they once had and blamed himself for being arrogant enough to think his love and trust can endure the harem shitshow, rather he absorbed "we used to be childhood best friends" into his calculus of 'who should I believe' every time a conflict arises. Soon Qianlong began to say "Consort Xian and I have known each other for a long time" as dispassionately as him saying that he appreciates Langhua or Consort Chun for birthing children for him. I think at that point Ruyi just lost the willpower because she knew that the old Qianlong was gone and there was no use fighting for it anymore.
