Mitsuaikon ~Gokujou Onzoushi to no Omiai Jijou~

Noriko, who manages her family's business of flowering, decides to go to a marriage interview in order to save the family business. Eager, she goes to the meeting place, only to find her natural enemy and boss, Renji Takatori. Being rich and handsome, he's very popular in the company, but Noriko doesn't do well with him makes snide remarks towards her whenever something disagreeable comes up. She thought the engagement would be cancelled, but forcefully continuing the topic of conversation, he says, "I was the one who set up this arranged marriage." Who would have thought that they would have to live together pre-marriage!

Unable to refuse her boss directly, she sets up a plan to make herself hated!

(from mangaupdates)