steadfastness

The quality or state of being steadfast; firmness; fixedness; constancy. «The steadfastness of your faith.» Col. ii. 5.

To prove her wifehood and her steadfastness.

noun

Faithfulness or devotion to a person, a cause, obligations, or duties: allegiance, constancy, faithfulness, fealty, fidelity, loyalty. See continue/stop/pause, obligation.

The noun has 2 meanings:

Meaning #1: loyalty in the face of trouble and difficulty
  Synonym: staunchness

Meaning #2: steadfast resolution