When aliens arrived on Earth, it happened with an invasion—just like the sci-fi movies taught us to expect.
The vicious Suhlik meant to enslave Earth and rob her of her resources. Only the Mahdfel warriors were able to stand against them.
Once the slaves of the Suhlik, the Mahdfel won their freedom. But as a lingering reminder of their oppression at the hands of the Suhlik, they are unable to have female children.
Now, in exchange for the protection of Earth, the hunky alien warriors demand only one price: every childless, single and otherwise healthy woman on Earth is tested for genetic compatibility for marriage with a Mahdfel warrior. If the match is 98.5% or higher, the bride is instantly teleported away to her new mate.