I think it's a bit ludicrous that people accuse Keiko of being a "god-awful, horrible bitch" while failing to cite even one specific instance in which she behaved in that manner. O'Brien, of course, was a Saint.
"Think about when the 2 of them are discussing about how they always eat what she wants to eat so she agrees to try his favorite foods. She complains the whole time he describes Irish cuisine then is discusted when it is laid before her and she barely tries it. I understand if she is vegan or something, but she was very disrespectful of something he enjoyed. "
There's one I gave yesterday. Or how about after Miles got her a trip to explore a region on Bajor for like 3 months and then she says she is going back for a few more weeks. She doesn't get his feelings about it, just tells him she's going. When he gets upset because he misses his wife and she just tells him she's going without getting his feelings, she tells him another guy on the expedition said he would over-react. Oh yeah, Keiko, Miles is going to like you and a dude you work with talking about how unreasonable your husband is.