Why did Antipas risk angering his FIL, the powerful King Aretas, by divorcing the man's daughter? Why rekindle the North Arabian grudge of the Nabateans against the Herodians? For love? For lust? For money? No, not even for money. Wealth means nothing without security, especially back then.
Herodias must be the key. Herodias and her patron Antonia, that is. If Herodias desperately wanted to be "Queen" of all Galilee, it's plausible she could have prevailed upon her childhood patron Antonia, her own mother's dear friend, for a reasonable dowry, at least. To assure peace in Palestine, however, was more than Antonia could peform... at least directly.
What Antonia did have the power to do, however, was get Antipas invited to meet with the Prefect Sejanus (in Rome) and/or Tiberius (on the Isle of Capri). Antonia may or may not also have called in some favors (or promised some) to request that the Emperor and/or his right hand man listen favorably to what Antipas would ask. And though we may not know what Antipas might have asked for, we absolutely do know what he got.
Antipas simply must have left Rome with assurance from someone that his marriage treaty with Arabia (which Augustus had been so pleased about) could be officially dissolved with Imperial favor. The premature flight of the princess may have upset the timing somewhat, but the peace evidently did hold. It was not until seven years later, when the Syrian province was in chaos, with Tiberius virtually on his deathbed (at age 69), that Aretas would finally take his revenge. The revenge was short lived, and Aretas himself died a few years after that, but the peace lasted at least three years after Sejanus fell.
Only Tiberius through Sejanus (or Sejanus alone) could have offered such a benefit to Antipas. But why would either of them give such a benefit? What did Rome stand to gain, from allowing Herodias to become "Queen" of Galilee?
We can point to a few possibilities.
To be concluded...
Read the Whole Series: Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Conclusion