I’m not much on the Bible, but I don’t think Delilah was Philistine. Otherwise why did the Philistines have to bribe her to find out Samson’s weakness.
Because she was a hooker and he was a steady customer who might have even been persuaded to offer marriage.
Samson's earlier wife was a Philistine woman from Timnath--her name is never given.
In the Septuagint, "Timnath" is Thamnatha and Delilah's name is given as Dalila or Dalida.