What is meant by the treachery of her own heart?

The phrase "the treachery of her own heart" refers to the internal conflict and betrayal one feels when their emotions or desires lead them astray from their values or intentions. It suggests a struggle between rational thought and deep-seated feelings, where the heart's inclinations can lead to self-deception or disloyalty to one's principles. This treachery often results in feelings of guilt or confusion, highlighting the complexity of human emotions and the challenges of self-trust.