undone,+possessed

It is a possibility that this situation is a love affair. The speaker uses sarcasm at the beginning of the poem to indicate that she is not a weak person, until she is with this man/woman. When she is with them, they ravish her and she loses control. She becomes "undone" and "possessed", which is out of character for her. This calls for racy imagery, although she is not specific, she clearly wants the reader to understand that the two of them don't just sit around knitting socks and drinking hot cocoa together at night. Using the word "undone" also implies a lack of clothing.