Yan Ye had obtained the note inside the music box three years ago and knew from it that Lian Jie wasn't dead, so he had been pretending to be the good guy in front of Lian Xinying, in order to, when Lian Jie appeared one day, join his mother to kill Lian Jie!
They had been putting on a show in front of her all along!
It wasn't until Ji Fan told Lian Xinying that Lian Jie had died that Yan's mother instantly showed her true colors and tried to kill her, that Lian Xinying saw through everything!
All of the above were Lian Xinying's speculations.
Yan Ye's repeated concealments, his repeated rationalizations, she had unconditionally believed him because she loved him, only to find out in the end that she had been deceiving herself and was fooled for so long.
Yan's mother couldn't stand listening to Lian Xinying scold her son any longer, so she snatched the phone from her and quickly turned it off.