Hiding the Vampire's King Son

Jaxon Hellscream is the future King of the Empire of Lair, where all the vampire is living and he has an ex that is Venice Alcen Bloodhoof that he have a relationship until she decided to break up with him because of her mate needed her. They are forbidden to love each other because their mate needs them to survive but Ajax loved her that he even begs for her to gave him six months to make their relationship worked and after that, they will both accept their destiny. But, because of it, she will be the Mistress of the Vampire's King because it's destined to be with his mate who is a mortal. Can they accept their fate or will choose to be with each other even though, they are not the ones in the prophecy?