In one of the worlds, Nan Yuan was fighting against a group of men and Xiao Tang pops a strengthening pill into her mouth which allowed the body she's in to break bones and throw the men over her shoulder like tr*sh.

Nan Yuan: "Xiao Tang, warn me next time you do that."

Xiao Tang, the best little protector in history was unrepentant: "I saw the situation was urgent. I would rather you maim outsiders than get yourself hurt!"

Nan Yuan:...I can't bear to scold him harshly.

In the first world, he went through great lengths to keep Nan Yuan's head maid alive so when Nan Yuan comes back she'll feel more at home. He also let Xiao Tang ride on his spider form so he can cheer up. In the sixth world, he would often take Xiao Tang out to play so Nan Yuan can focus on her training.

Nan Yuan is slowly opening up more. Xiao Tang is getting more pe*verted from reading his father's notes. The ML is hard to say because he doesn't retain the memories of his previous lives. But if I had to say something, it'd be he's gaining more confidence as Nan Yuan's lover.

One of the people she met in the fifth world was an emotionless killer who later gets amnesia and falls in love. When she sees him later in the story, she's suprised by the vitality in his eyes and how he can express his joy. Nan Yuan acknowledges that she's just as emotionless as him, so that makes her wonder if maybe she should get amnesia too. But then she dismisses it because why would she ever do that to herself?

Then a reason finally comes: when the ML is dying of old age, he confides to her one of his biggest insecurities. He's always questioned whether Nan Yuan really loves him because he would give her all the love he can offer but she was still calm and indifferent. Nan Yuan does care about him, otherwise why would she bother to stick with him in that world and the previous ones, but she admits she probably can't give him the love he seeks because of the long life she's lived. A classic case of "you were a wonderful experience/ you were everything".

Nan Yuan then decides to cast a spell on herself to block her memories when she goes to the next world.

In the next world, she wakes up only knowing her name and the memories of the body she's inhabiting. She gets falsely accused of colluding with a demon cultivator and attacking a fellow sect member. Instead of crying and begging for someone to believe her, she endures 80 goddamn lashes and then clears her name by casting a spell to project the memories of her soul which comes at the cost of her cultivation. Then, to the horror of everyone present in her trial, she digs out her golden elixir and crushes it. Her reasoning? If her cultivation and elixir are gonna be destroyed anyway, she'd rather do it on her terms. She then takes off her sect clothes and gives back all the things they have given her, decisively ending her relationship with her sect. She walks out of the sect, back straight and covered in wounds, but full of dignity. She doesn't know who she is. Doesn't remember her training or experiences. But that doesn't mean she'll allow anyone to trample on her.