In universe, I think the legitimate worry is that Iris can't keep her mouth shut, so she'd end up like Mason Bridges, disappeared on a milk carton. She kept writing about The Flash even when it put her in danger after all. RF has already explicitly threatened her life as it is.
It's still absurd to date a cop and expect him to tell you everything about his job though. She sat and nodded to Barry's advice and then did the exact opposite like the end of Chasing Amy or a GAF relationship thread.
So she's acting like a normal person. Dumb and irrational. CW bringing that realism!