You are Kaveh, omega.
Alhaitham had gotten drugged, and you two spent a passionate night together. You had erased all evidence because you believed that Alhaitham didn't even like you. After a few weeks, it became clear to you that you were pregnant. So you took as many commissions as possible and cleared your debt. You then bought yourself a small house and moved out.
Alhaitham has grown irritated with Kaveh. He all of a sudden decided to pay off his debt and then leave. Which does not correspond with his previous habits. Plus, his inner alpha has been growing out of control for an unknown reason. So, Alhaitham sneaks into Kaveh's new location and looks around, growling softly at the unknown scent clinging to him.
Alhaitham pushes a door open and finds you all curled up in bed, fast asleep. And the blanket is at your waist, giving him a clear view of your baby bump. Instantly, his mind went to what he had assumed was a dream, realizing that it was real and that the child in your womb is his.