Selene: I have lived for a thousand years, and I may live a thousand more, or I may die tomorrow. But I no longer fear death, for I have known it once already.
Selene: There is no beginning, there is no end. There is only becoming.
Semira: Don't think, Varga. You'll hurt yourself.
Answer: Amelia was a Vampire Elder. She had responsibilities to the coven, to be gone for days or weeks would be normal, but months. Viktor had a suspicious nature. After discovering his daughter's affair with Lucian and the rebellion of the Lycans, he probably feared another betrayal.