This is my theory.. I mean LS was being emotional, telling everyone to take care and this and that in jiaxing village. Then wuyi came.. he said something. Our girl got heartbroken , screamed and cried then went away along with her jiejie. Maybe it's like tribulations type of thing. So she thought why can't I do it. Then I won't have to lose jiling again. But before she could do anything everyone found out and came to stop her.
No. Bcoz we've seen LS with the ring again. Wuyi must've given the ring back to him. So there's no way she could've done something that can harm anyone.