If An Zihao admitted to creating a fake recording, Tangning's innocence would be rebuked and her scandal would ignite once again.
It would also mean that An Zihao's methods were like a poor lie which backfired because it would seem like he really did have something to hide; he was hiding the fact that Tangning's private life was a mess and she had ambiguous relationships with quite a few men.
Taking everything into consideration, An Zihao was put in an extremely difficult situation. Amongst his options, he didn't mind getting hurt, but he didn't want to hurt his dead lover, nor did he want to hurt a living friend.
...
After returning discreetly to Beijing, Tangning contacted all the friends that could possibly lend a helping hand. She wasn't afraid of starting a battle with Lan Xi, she simply wanted to find the best way for An Zihao to retreat.
I feel so sorry for An Zihao. It's so sad that his lover died and he hasn't been able to move forward.