Find a Book Where the Heroine's Surname Is Gu and She Becomes the Hero's Cannon Fodder Ex-Wife.

The female protagonist's surname is Gu, and she must be quite rich. The male protagonist's surname is Cheng (it seems) and he is the boss of a company that engages in programming or something. The female protagonist does not know his real position. When the female protagonist walks in, they are already a couple. After falling in love, the male protagonist prepares a cardboard box for the child.