Male Alpha, female Omega / marriage first, love later / chasing his wife to the crematorium (but it doesn't work) / one of the second male leads wins her heart
Pheromones can't create love, but they can create the illusion of a harmonious marriage.
August, the Empire's regent, married in accordance with his family's wishes. His petite wife was beautiful and gentle, like a fledgling sheltered beneath his wings. Most importantly, she was the only Omega on the planet whose pheromones matched his with 100% compatibility. The regent was satisfied with the stability of their marriage and planned to carry on like this.
But after he brought back another Omega from an enemy planet, August noticed the fire in his wife's eyes had gone out.
Later, August discovered that his longtime friend, his loyal subordinate, and the promising rising star of the military were all top-tier Alphas who had fallen at the feet of the same person: Ying Xu, his wife.
Only then did August learn that Ying Xu had 100% pheromone compatibility with every top Alpha.
Theme: Set aside prejudice and cherish your relationships.