Songfacts®:

• According to the Songfacts dictionary, a "flux" is a "state of flow or continuous change." This piano-driven ballad finds Goulding contemplating on how her life is in a perpetual state of change due to the nature of her busy lifestyle, yet she's unable to let go of a past love.
  
  I'm still in love
  With the idea of loving you
  It's a state of flux
  But it's not enough
  
  Goulding is reflecting on how her life in the public eye, during which she's touring nonstop, has taken a toll on her relationships.
• Goulding took inspiration from different relationships and stages in her life for this song. She told The Guardian: "Flux is about thinking about the person who you almost ended up with - I'm a sucker for what could have been."
• Jim Elliot and Joe Kearns supplied the production. Their stripped-down accompaniment of piano and strings allow Goulding's vocals to soar above the instrumentation as the production intensifies. Eliot and Kearns also produced together Goulding's Delirium track "Scream It Out." Both have individual credits on some of the songbird's other tunes.
• The black-and-white video, directed by Rianne White, shows Goulding in an empty warehouse playing piano in the pouring rain as she reflects on the pain of an unfinished love. White is known for her work with the Scottish hip-hop trio Young Fathers.