Sang'er could have declined the task from Suri, but it was because of him that she took it up, accompanying him to White Blind Mountain, enduring so much hardship.
If anyone should say sorry, shouldn't it be him apologizing to Sang'er?
But...
He didn't want to say sorry to Sang'er, because those three words, in truth, were of no use. Saying them more wouldn't make things any better, and instead, because of these three words, those who did wrong might be easily forgiven.
So, he thought he wouldn't say those three words to Sang'er, because he would prove through his actions that he would not let Sang'er encounter such incidents again.
"Sang'er, it has been confirmed that it was Princess Consort Lian's close confidant who deceived Sui Zilin along the way. It was only outside the gates of Shaohua City that Sui Zilin lashed out, killing Suri in one strike,"
he said.
"As expected, it was her."