Reiguu Muko Life wo Mankitsu shiyou to Shitara, Dekiai Route ni Hairimashita!?

One day, ordinary office worker Kaoru Kusakabe (28) dies in an accident and is reincarnated into the world of a BL Omegaverse novel. Kaoru is reincarnated as Chris, an Omega and the concubine of Allen, the Alpha King. However, in the story, Chris has a child with Allen, but since his son-in-law has already has a child, he and his son are destined to be assassinated. In order to avoid his own death, he plans to disguise himself as a defective Omega who cannot give birth and live the life of a cold-hearted husband, but Allen begins to dote on Chris, whose personality has changed...

(Source: Shueisha, translated)