In The Boarding House, Polly is a victim of her time. Her mother was barely able to escape Polly's abusive and drunk father but managed to get a separation - not a divorce which would have been illegal - and she sets herself up in a boarding house to provide for herself, Polly and Jack, Polly's brother.
Polly does have a perception of her situation and how she has limited potential for improving her circumstances. It is a "wise innocence" that she possesses when she almost seduces Bob Doran. Having " the run of the young men" who lodge in her mother's boarding house, Polly flirts but there is little potential in these men who are "only passing the time away." This is a fact that her mother, Mrs Mooney, is all too aware of.
When Polly and Bob Doran become involved, Polly's mother's "tolerance" as she does not interfere, does not escape Polly's notice. When Mrs Mooney finally decides to intervene, Polly does not want to appear to have been complicit in any plot to catch Bob Doran out. She does have real affection for him.
Polly is kind to Doran, warming his meals for him on occasion and preparing him a warm "punch" when he comes in from inclement weather, but she is also young and "the blood glowed warmly behind her perfumed skin" when she comes to him for assistance with her candle. It is a seemingly innocent gesture but, as pointed out, not without some understanding of what she is doing. Bob Doran does have to accept some responsibility for what happens as they "exchange reluctant goodnights" but it is certain that it is "not altogether his fault."