One of the highlights of the 2016 presidential election season has inarguably been the antics of Republican frontrunner Donald Trump. He's said and done things that would have spelled disaster for any other candidate, but the notable instance among these has been his rivalry with Fox News host Megyn Kelly.

The bad blood between these two runs deep, and it started when Trump made a comment about Megyn Kelly's blood in response to a question she asked during first primary debate. It has since turned into a back-and-forth between the two and even escalated into a feud between Trump and the entirety of the Fox network. However, even when that rivalry subsided the rivalry with Kelly survived, and now she thinks she knows why.

Talking with Charlie Rose in an interview that will air this weekend on "CBS Sunday Morning," Kelly gave a theory as to why she has been exclusively singled out by Trump even though many other journalists - like her - have been quite tough on him.

Rose: "Some think about this, and they look at it, and they say, 'Why her?'"
Kelly: "I think it's very clear to him that he cannot control the editorial on my show, or from me, in a debate or other setting."
Rose: "Just that? That's all it is?"
Kelly: "I wouldn't want to speculate beyond that."

This is clearly an incomplete answer. Rightfully so, of course. The last thing anyone wants is to give Trump ammunition, especially since he has made a habit of destroying anyone who has.

All Kelly said was that Trump is frustrated by his inability to control her, which doesn't seem like much on face value, but it speaks volumes if you know some of their history.

What matters to Trump - and to all candidates really - is exposure. As the host of the second-highest-rated program in cable news - and on a conservative network no less - Kelly would be a prime place to start. However, this has not played out exactly to his plans. In a piece in Vanity Fair, Kelly alleges that he would try to woo her by sending her press clippings signed "Donald Trump" and personally called her on occasion to compliment her on a segment. As it turns out, all this came shortly before he announced his candidacy for the White House.

Kelly was unresponsive, however, and its effect was two-fold: not only did it mean that Trump would not get the exposure he desperately wanted, but it also meant that he failed in wooing a woman he tried to court. As you may or may not know, Trump is quite used to being popular with the ladies and even made headlines in the early '90s when his soon-to-be second wife, Marla Maples, gushed that Trump was the best sex she had ever had.

With that in mind, his actions - and her reasoning - become clearer. It also explains the discrepencies in his actions with other journalists. Remember during the town hall session with Trump on Tuesday when CNN's Anderson Cooper essentially called him a 5-year-old boy? There was no Twitter follow-up for that. Trump didn't call Cooper any names, and he certaintly didn't retweet any seductive photos of him from GQ Magazine. But then again, maybe he would have if Cooper was on a network that pandered to a conservative audience.

So in the end we're left with a rivalry based on ego and resetment. Trump might really be just upset about the one that got away.