Now...as for Ms. Hark's catergorizing of Ezri/Julian as "long-term", I think it has something to do with the gradual build-up to their eventual kiss.
It makes it believable. At
first Julian seems to want to continue the flirting he did with Jadzia (to Ezri, anyway)--and Ezri basically gives him the cold shoulder on that. Still, something clicks in their first meeting, and they become friends right away.
We then see them interact more and more, getting closer and closer together. (One of my favorite Ezri/Julian moments: In "Prodigal Daughter", just after the opening credits, as he sees her off. They have a moment of fun interaction with each other. Check out her smile when she asks where his report is.

)
I think the big moment between them--when the romance started to simmer (without either of them realizing it)--is in "Field of Fire", as the two stand over Illario's coffin. The way he supports her, and the way she accepts is, is very touching--and makes me look forward to the day when Julian mans up and proposes....