But what about if Arsinoe knew of Antony's plan to invade Parthia? You think she still would've gone there, knowing that if the Parthians lost, she lost?
What about Thrace? Would that work?
Just refuge. A little less desperately ambitious than Cleopatra, she simply wants to secure her life. That's why I originally thought Britannia, because she's used to doing without in Ephesus, and Britannia is remote and far enough away from Rome and Egypt.