The actions that you have described fall under the category of zina or fornication. Zina is not simply intercourse; there are steps prior to it which is also referred to as akin to zina. The Prophet (peace be upon him) said, "Eyes fornicate; the fornication of eyes is lustful looks; ears fornicate; fornication of ears is hearing; tongue fornicates through speech; hands fornicate by holding; feet fornicate through walking; heart fornicates by lustful thoughts; it is consummated by the private parts."
In light of the above, she is undoubtedly guilty of transgressing the limits of Allah.
It is best for her to put a stop to this and ask forgiveness of Allah through sincere repentance. Otherwise, she is risking her faith and honor. Fornication is undoubtedly a grave sin.
For further details, you may consult the following answers.