Answer: They emphasize Vivien's adamant decision.
Explanation:
The stage directions revealed that Vivien has made an adamant decision. In this case, we can deduce that Vivien was going to do everything possible in order to get him.
This can be seen when she said that even though she had never wanted anything badly enough before but that this time, she could cry her heart out for him with no pride left and that she was going to have him.
The word you could possibly be looking for is "intent"
It’s not really that confusing..