Mistress Enola had paid her instructor a lot of money for his services but he was distracted and she did not like it. She had to ensure he concentrated and did what she wanted. That is why she went out of her way to trample on him and to spit on him so as to get him to realize he had to put his act together and do what he was supposed to do.
Mistress Enola did not want her boyfriend to continue being boring. She wanted him to try and be a little bit spontaneous and exciting but he did not take any step towards any of that. She was feeling frustrated so she used her spit to dominate and to humiliate him so that he would realize that she was serious in whatever she was saying and whatever she wanted him to do.