Since I never liked Keiko, it would have been interesting to see how a Miles/Kira pairing could have turned out. The best romances start out as friendships, so it wouldn't have been a "one day _____ realized that the love of his/her life was right under his/her nose all the time!..."
- he's married and in love with his wife
- he is not her type, and she didn't and wouldn't have ever felt any "attraction" to him if it weren't for the baby situation
- they were never even particularly close friends, just co-workers
- the "attraction" that was there for, what, 5 minutes? only happened because she was carrying his - and Keiko's - baby. That may be understandable on some level, but it's also
on so many levels.
It generally makes no sense - but hey, I suppose "I HATE KEIKO" trumps all these arguments...
I am still not sure which romance would be less believable, Kira/O'Brien or Jadzia/Horta.
The latter would probably be more exciting and interesting, though.