Maybe she is going to a store of boys and buying one, so she pays the boy, and after that goes home.
Could be "LOL" if recent news weren't so perverse regarding abuse of children.
As a native English speaker, I have never used, nor have I heard anybody use the phrase "pay to."
It feels more natural if you add an object. "She pays money to the boy"
Is this "She pays for the boy", like she pays for whatever the boy has spent or taken?
That would be "Αυτή πληρώνει για το αγόρι" (για = for).
"Αυτή πληρώνει το αγόρι" means that she gives money to the boy.
Like, she pays TO the boy?
Αυτήν πληρώνει το αγόρι. and the subject of the sentence changes.