Why should the young woman be responsible for other people's pledges? She has made no promises; she is her own person to give where she pleases. She may be foolish to risk emotional involvement with a man already committed elsewhere, but the moral obligation of marriage vows surely belongs entirely to the maker of the vows.
It is extraordinary that the injured wife always seems to blame the 'other woman', who owes her no obligation, rather than the husband who has promised to love and cherish her. The old adage that a woman's place is in the wrong seems to die very hard.