i think thats because her son is dominant omega and engaged to the crown prince and have aggreement or something with the imperial family
That is not enough of an excuse to keep it a secret from him tho
His mom said he basically never showed any omega characteristics like pheromones or heat unless the crown price was around, so basically, if he never met the crown price, he could've lived like a normal person who happened to be a dominant omega but never had any of the symptoms that come with it. It was fucked up that she didn't tell him, but she also said she was getting money and protection for him the entire time he has been engaged to the CP, so he wasn't in danger at all.
Tbh I'm more .mad at parents than the CP. Like how the mom gonna say she's proud of her husband but still hide the fact that their son is an omega. Hypocrisy at its finest. And the excuse "oh you didn't show any omega-ish behavior" like bitch bfr.
What were they going to do if the MC suddenly got into heat and got graped (worst case scenario) not knowing why nad what he did to deserve that.?
There are so many worst possibilities to imagine and they kept it a secret.