Definitions of unbend:

• verb:   release from mental strain, tension, or formality

  Example: "Unbend the mind from absorbing too much information"

• verb:   free from flexure

  Example: "Unbend a bow"

• verb:   unfasten, as a sail, from a spar or a stay
• verb:   make less tight
• verb:   straighten up or out; make straight
• verb:   become less tense, rest, or take one's ease