He indicates a time when emotions are running high, but are difficult to express (and therefore, to put into action/motion, to realize or to actualize).
Whether that emotion is romantic, brotherly, platonic or sexual really wouldn't matter so much as the fact that this person is feeling these feelings deeply, and is somewhat reticent (or just plain unable) to express them, and/or to act upon them.
The card could reflect on a business deal just as much as a relationship, so don't get locked into the notion the K of Cups is "the Lover" as he's often stereotyped.
Unrealized passion can indicate a professional desire to bring something into being (a business, a project, whatever) but being unable to do so, due to finances, timing, or any other obstacle.
IN essence, the K of Cups means the emotions are there, and plentiful, but they aren't *going* anywhere. They just exist, and need more direction.