It was never answered. It was left to our interpretation. This was one of my favorite episodes. Even better if you're a fan of Rashomon.
I get the impression they were each attracted to the other, and both took it too far, and are in denial. The wife moreso than Riker, because in her version, Riker is way out of character to be believable.
I don't know if it was a scriptwriting accident or intentional, but Riker makes a Rapunzel reference in the wife's version of events. An alien like her probably would have never heard of Rapunzel, meaning that she wasn't making that up, or it was a mistake.
In Riker's version of the intro where the wife is coming on really strong, LaForge was there. Did he notice? Was that a combined testimony, or just Riker's perspective alone?