We've seen Rory in all of two sexually intimate relationships- Dean and Logan- and both involved episodes of jealousy, infidelity, and doubt in Rory. So no, I would argue the opposite: we have no evidence that Rory is at ease with FWB situations or casual hookups; if anything she fails at her FWB attempts quite spectacularly. Her freak out over Mr. Wookie serves to underline that point.
As for Paul, the fact that he was seemingly created for comic relief flattens his character considerably. But what we do know is that he had been dating Rory for two years, had met her mother, her grandmot