[ This is not something that Jiang Cheng has spent a great deal of time rationalising; he hadn't dared think too hard about the operation, about the fact that Wei Wuxian had risked so much to give up his own to his martial brother. He knows that if he had been asked he would have refused, that eventually he would have come to terms with the loss of his core, that he might have found some other strength, but...

Bowing his head, he closes his eyes and fights back the rush of tears that prickle at the corner of his eyes. The pain he had felt knowing that Wei Wuxian had made this choice, his own cruel words in the wake of the loss, knowing that he had been part of the reason his brother had fallen into Demonic Cultivation was all tied up with his rage and anger - at being denied a choice, at something of his being risked without consent.

There had never been anyone he could speak to about this, no one he could unburden himself to, until now. With marriage as a protective barrier he feels as though he can confess all his sins and not be shunned for it.

Shaking his head, he barely lets himself look at Xichen. ]

I didn't find out until Wen Ning told me at Lotus Pier. The night we found out the truth about Jin Guangshan's death.