He said in an interview that he always considered Garak to be gay as all get-out, and thought that it was perfectly obvious, and that Garak should've had an affair, preferably with Bashir.

Andrew Robinson's vision of the Garak's character was that he was sexually attractred to Bashir right from the start. Playing this openly would have been way too much for 90's TV, so he stuck to the idea but downplayed it. Which most likely is the reason why the interaction between these two characters was so great.