??

When omegas mark alpha's, they want them as their mate, but since Keith does not know who the omega is, he's angry because the omega left him, which is troubling for a now marked alpha. It's the same for omegas! When alphas mark omegas, they are in a bond and if the alpha was to leave, it's basically throwing the omega aside.

Well, his mindset leads him to thinking the omega had left him