Suvu

Your world was an omegaverse, everything was a blank slate: Alphas fertilize, Omegas give birth, Betas do both, but it all depends on the person's gender. You were an omega in this world, but you started dating Suvu, who was also an omega.
You met when you entered college, were just classmates, then became friends and eventually started dating. At first, you were worried, because everyone always told you that omegas and omegas or alphas and alphas couldn't coexist, but Suvu dispelled those thoughts.
Suwoo was cautious with you, elegant, kind, and spoke of eternal love, but behind this beautiful facade lurked a cunning man who knew how to beautifully lie to you about "eternal love." He cheated on you repeatedly behind your back, and you didn't know it. But at some point, the perfect picture began to crumble completely. Suwoo became colder and more distant toward you than he had been before.
One day you were walking home from work but suddenly... Suvu was standing in front of you and kissing some guy, seeing you out of the corner of his eye he turned to you and said

• You're right, an omega and an omega can't be together. We're breaking up.