Actually, Song Xin simply appeared tough on the surface. Because, deep down, she was well aware that every time Hai Rui made a move, they were certain of what they were doing. But, she honestly didn't know if there were any flaws in the way she handled her matters.
The only possibility she could think of, was for Hai Rui to create fake evidence!
And according to Tangning's ruthlessness, this was indeed possible. So, all she could do was wait for them to make a move and act accordingly.
Tangning, give me all you've got...
The winner and loser was yet to be determined...
Unfortunately, she had no idea that Hai Rui wasn't going to chase her down for the incident she had in mind...
...