Wait at the end of Blue Moon i don't get want Roman did so Ever and Damen couldn't be together? Could someone explain?

Roman was making Damen mortal by messing up his elixir. Romy and Rayne(?) were making a solution to cure him. Roman had that same cure, but he added Ever's blood to that which somehow made it so that he was cure of what he had before, but he couldn't be with Ever.

i think he put a curse on damen and ever. if they touch damen will die