Looks like uke alpha becomes an omega after repeated sex with another alpha and he gets raped by a third party. The seme is evil incarnate and the ending is foul.
Summary...The seme is nuts and evil to his core there is no happy ending to this story. First, he took the uke's gfs and left him thinking he wasn't worthy of love from omegas. Crazy guy also bit all of them so they're bonded for life, if I remember right. Then they meet up as adults and he turns the alpha uke into an omega against his will. He put holes in the condoms to both push the alpha to omega transformation and to get this guy pregnant. This poor uke is so screwed when he learns the truth of how his life was ruined along with his body.
Imitation Mate