I think that Sisko and Jadzia were just good friends in the real universe. I never remember any hint of sexual attraction.
He did have a couple double-takes at the sight of our Dax in a classic 23rd century mini-skirt. And, no doubt, a moment of reconsideration.
Tina Lawton wrote:
I always thought he "slept" with her to maintain his cover.
Yeah, it was important that he maintain discipline among the crew - the Mirror Sisko way!