@Era1 Goes with the job. And she takes no shortcuts with her job.
@Heimdal Hardly any guessing needed anymore. He sent Shirayuki away to gain recognition, fame, and connections so that she would have some standing to be beside a royal prince. I suppose as a king he could have allowed the marriage even without such things, but this is far better for two reasons: It's extremely good for Shirayuki's own career (that's basically her first priority anyway, with Zen coming as a distant second) and one the other hand, if she's a well known person throughout the kingdom, nobles and other important people won't so quickly look down on her. It would be sad for her to be a prince's wife if people were all the time whispering she's a nobody who somehow seduced a prince.