Please recommend a novel in which the male protagonist keeps the female protagonist.

The female protagonist was kept by the male protagonist and signed a two-year contract. Then, the male protagonist did not make things difficult for the female protagonist. The female protagonist felt that although she was kept, she was still very lucky to meet the male protagonist. She treated the male protagonist very well, but after two years, she left. The male protagonist did not realize that the contract had expired at first. Later, the secretary or assistant reminded the female protagonist to come back.