Falling for the Enemy(2007)

Boss wa Shukuteki

"This man is my boss…and my father’s enemy.” Bryce’s dirty tricks drove Paige’s father to his death. Now she slips into Bryce’s company as a secretary in order to find out his weakness. However, he doesn’t trust her and is trying to discover her motives. They’ve both been keeping their suspicions a secret, but now the seeds of a dangerous love are beginning to sprout!

(Source: Harlequin Comics)