Blood Rose - Road to Immortalism

Devanna and Scarlet are two flat mates living in the London. Things were all right until Scarlet gets married.
After Scarlet's marriage Devanna tries to manage her living in London all alone. But Scotland brings about a drastic change in Scarlet.
Jealousy, Revenge, Hatred, Possessiveness turns the relation sour between once soul sisters.
What exactly brings the change?