Blake has always had his creepy 'Too old to be a big brother' relationship with young females on his team. Remember Xenia? Nobody but him thought she was that good. He had one every season.
But I'm sure they selected that song for purely pandering reasons. Any emotion expressed in a song sung by either Blake Shelton or Danielle Bradbery is by definition insincere, so I have no doubt they have no real romantic feelings for each other.