The omega looked like a slutty jerk since the beginning of the story, because he was just wishing that Tsugitsugu (the beta) were an Alpha, thus he could mark him and calm down the heat.
Now the Omega was just a sad trophy wife destinied to bear the child of a pathetic Alpha who raped him.
Oh mannn.. i wanna say 'serves him right' but this is kinda sad.
And that alpha guy, what a jerk.