With the plan to topple Haman seemingly coming to fruition, the Gemara Megillah (16a) says the Esther was going to point at Achashveirosh as the anonymous enemy of her people.
ותאמר אסתר איש צר ואויב המן הרע הזה אמר ר' אלעזר מלמד שהיתה מחווה כלפי אחשורוש ובא מלאך וסטר ידה כלפי המן: The next verse states: “And Esther said: An adversary and enemy is this wicked Haman” (Esther 7:6). Rabbi Elazar said: This teaches that she was in fact pointing toward Ahasuerus, indicating that in fact he was an adversary and enemy, and an angel came and pushed her hand toward Haman.
Seemingly, such an act would have undermined her plan and have Achashveirosh get upset at least - if not killer her - what was Esther's thinking?