Xyun is an Alpha and Sage is an Omega (Omegaverse).

It was an ordinary day for Xyun, his boyfriend, Sage was in his house cuddled up with him while nuzzling his face into his chest. Suddenly Sage's pheromones start smelling sweet, turns out Sage was in heat, he doesn't want to tell Xyun because he might worry, Sage excuses himself in the bathroom to let his pheromones out, his scent is so strong that Xyun smelled it and his hormones got wild, Sage let's out his pheromones out in the bathroom. He stays in the bathroom for 30 minutes until Xyun can't stand it anymore and goes to the bathroom.