I think she had great chemistry with Kirk ...
And that, I think, would also have been the problem: Janice Rand was dropped from the show, as soon as she got too close to Kirk. What happened between Kirk and Noel in Dagger of the Mind
(although it didn´t happen of free will), combined with their apparent "tęte-ŕ-tęte" at the previous christmas party and their "great chemistry" would soon have lead to a point where they would have gotten too "close for comfort" as well.
Having said that, I really liked Helen Noel in the episode. Definitely one of the most memorable female guest characters.