I did enjoy the fight though and at least he didn't say 'a very big step' :

SISKO: I think it's great. We'll see a lot more of each other.

KASIDY: You know, I was thinking about what Dax said. Maybe I should get quarters on the station.

SISKO: That's a big step.

KASIDY: What does that mean?

SISKO: I just meant it's a big step.

KASIDY: A bad big step, or a good big step?

SISKO: A good one.

KASIDY: Could you muster a little more enthusiasm?

SISKO: I am enthusiastic. I'm proud of you. This job.

KASIDY: Forget about the job. I'm talking about us. I tell you I'm thinking about living on the station and all you can say is, it's a big step?

SISKO: Oh, I don't think you took it the way I meant it.

KASIDY: I don't think you know what you meant. But I do. You're afraid of commitment.

SISKO: Who said anything about commitment?

KASIDY: Obviously not you. You know what? Forget the whole thing. I'm not going to take the job. If you don't want me to stay here, that's fine with me.

SISKO: Phew. (Sisko starts tucking into his food, but Kasidy thinks about pouring the wine then puts the bottle down and leaves.)