After going on a rant about it I have to share it here:
Qi Yunke was only really bothered by Mu Qingyan when it became clear there was a possibility of Cai Zhao sticking with him. Genuinely, we only ever hear about Qi Yunke's relationship with Cai Pingshu from outside perspectives, and his own, and to be totally honest, I don't trust his perspective. She was in love with the Skin-Painted Demon (I'm not going to spoil his identity), so Qi Yunke's love was obviously unrequited and its very clear he is not as honorable and upstanding as, say, Song Yuzhi, so while I accept that Cai Pingshu likely truly saw him as a good friend, I don't trust that Qi Yunke (who I despise) would let go so easily.
Cai Zhao seems to be what he's holding onto at this point. "Protecting" her from Mu Qingyan is the flimsiest fucking reasoning ever, given that he saves her and she saves him and he makes her soup and she makes him those smiley things and they OBVIOUSLY hold each other in VERY HIGH REGARD and that's where Qi Yunke deems the problem.
The thing is, though, that no one could have possibly expected Cai Zhao to not be incredibly independent. There was literally no way she would just go along with other people's plans for her. But everyone is CONSTANTLY trying to get her to follow along with their plans for her. Going to Qingque sect. Getting married. Staying on the mountain. Getting her away from the cottage when Mu Qingyan arrives so they can ambush and kill him to "protect her" because they're so obviously the good guys. Etc, etc, etc.
The point is, everyone tries to control her, and they consistently fail.
Mu Qingyan is something she genuinely chose for herself, one of the few things really. And this thing, this person she chose for herself allows her to live as honorably as she was raised to be.
That's what's so crazy. It's when she's with Mu Qingyan that she's able to live entirely by the principles and values she was taught, and they don't like that.
Her aunt taught her to be honorable, and she is, but the Six Sects continuously prove themselves not to be. Her aunt taught her to defend those who can't defend themselves and the first person she finds herself defending upon arrival at Qingque Sect is Mu Qingyan (or Chang Ning) and she's defending him AGAINST the Qingque sect disciples. She helps Mu Qingyan because she's good and honorable, and he has continuously proven himself to be good, so why shouldn't she help him.
For the most part she has followed the path others have chosen for her, but when she chooses Mu Qingyan, she deviates. They realize they're losing control, and they take drastic measures.
And specifically Qi Yunke cannot abide Mu Qingyan having any claim to Cai Zhao's loyalty, and as it becomes more and more clear how much of her loyalty and love lies with him, Qi Yunke and Co's actions grow more and more drastic until they decide to ambush him 4 on 1 with intent to kill him. And they knew Cai Zhao wouldn't allow it, so they tried to keep her out of it, because they knew she would FIGHT ON HIS SIDE. And she did. She went so far as to not only shield him, but strike at Qi Yunke, before ultimately threatening to take her own life.
When she goes to visit him while imprisoned, she knows Qi Yunke is there. It seems she has come to the realization or resignation that Qi Yunke is not the honorable man she had thought because she puts on a show. She makes it seem as though she is abandoning Mu Qingyan. We know she hasn't.
It's almost like the women in her family are cursed to be incredibly capable and honorable and thus wanted by all as a pawn, but when they refuse to bow to the whims of those who think they are in control of the chessboard, they're disparaged or their stories are changed or their credit is taken from them.
And, like she said in the beginning, Cai Zhao's story is shaping up in a similar way, we can only hope she breaks that curse.
Anyways, that was my ramble.