Each justice or judge of the United States shall take the following oath or affirmation before performing the duties of his office: “I, XXX XXX, do solemnly swear (or affirm) that I will administer justice without respect to persons, and do equal right to the poor and to the rich, and that I will faithfully and impartially discharge and perform all the duties incumbent upon me as XXX under the Constitution and laws of the United States. So help me God.”Breach of oath = removal from bench.
She didn’t breach her oath. Judges are empowered to perform marriages, but are under no obligation to do so.