谁 as relative pronoun?
Chinese does not have relative pronouns. In the case of the sentence that you gave, it would probably be best translated using "因为" (because):

至少今天她都不想再见到聂离了, 因为她让聂离骗了她 or in English:

At least for today, she doesn't want to see Nieli again, because she let Nieli deceive her.

EDIT:

In Chinese, instead of using relative clauses, particles like 的 are used instead. For example:

The man, who learns Chinese, is here.

学汉语的人在这儿。

In the above case, we use the fact that the person learns Chinese to describe said person, instead of having a relative clause.