He left Aelflaed in order to marry Eadgifu, who gave birth to Edmund I, the future king.
Edward’s marriage to Aelflaed must have ended in the late 910s, so she could leave the series imminently.
The king did not have his wife killed in real life, but this may be where the show utilises its creative license.
There is a chance the young king could make his wife pay for conspiring against his mother.
Clarkson is due to appear in the fifth and final season but at this stage, there is no knowing how long she will last.