The pursuit, however, failed.

Demetrius had anticipated, or at least feared, a change of purpose, and, having prosecuted his journey with the greatest diligence, had reached his own territory before the emissaries of Phraates could overtake him.
It is uncertain whether policy or inclination dictated the step which Phraates soon afterwards took of allaying himself by marriage with the Seleucidae.

He had formally given his sister, Ehodogune, as a wife to Demetrius, and the marriage had been fruitful, Rhodogune having borne Demetrius several children.

The two houses of the Seleucidae and Arsacidae were thus already allied to some extent.

Phraates resolved to strengthen the bond.