Why would there be Romulan ships on patrol around DS9? The station is already defended and the Ninth Fleet with Klingon and Starfleet forces seemed to be based out of there given how often Martok was around. The station didn't seem to be at risk since the initial attacks of the war and even after several months after it was recaptured the Dominion never threatened it again, so why would the Romulan waste their ships there?
The start of season 7 we hear the Romulans aren't using the station for medical needs instead going to their own space. We do hear of Romulan ships been at DS9 later in the season and there are concerns about shore leave for the crews due to the Klingons on the station. This with the also mentioned slowness to get to the Romulan ships in the same episode would make DS9 a less attractive option to visit. Given these things it isn't that surprising we see so little of the Romulans at DS9, apart from major joint operations