Tomoe Marguerite

A secondary antagonist of My-Otome as well as Coral No. 2 and a room attendant for Chie. Tomoe is a cruel devilish manipulator who uses weaker people to get what she wants. She hates Arika and try, by using Chie, to kill her among the series. Although she usually disguises her malicious intentions with an image of perfection, her vulnerability shows when Shizuru (for whom she harbors romantic feelings) is concerned. Near the end of the anime, Tomoe joins the dark side to be able to kill Arika with her own hands, but she loses to Arika and is reported as dead (even if she is alive...). Tomoe returns at the next season (Mai Otome Zwei) as a mayor's wife.

Yes, she married him so she would be rich and have power to continue trying to kill Arika. She tries again and fails again, this time probably finally giving up. Tomoe appears in the manga as a good and sweet secondary who doesn't even have lines, so it's assumed that her personality is just cruel in the anime version.