fidelity vs two-timing

fidelity

• Accuracy, or exact correspondence to some given quality or fact. 

• Faithfulness to one's duties. 

• Loyalty to one's spouse or partner, including abstention from cheating or extramarital affairs. 

• The degree to which a system accurately reproduces an input. 

two-timing

• The practice of being sexually or romantically unfaithful. 

• Sexually or romantically unfaithful.