Historical clue formulations

• Engagement, quaintly — 2025-04-08
• Loyalty that's pledged — 2022-03-06
• Loyalty, old-style — 2017-09-09
• Fidelity — 2013-03-24
• Something plighted — 2011-09-11
• Loyalty — 2010-10-02
• Loyalty — 2009-04-17
• Lovers' plight — 2007-11-04
• Something to plight — 1994-09-27