plight

before 1000; (noun) Middle English; Old English pliht danger, risk; cognate with Dutch plicht, German Pflicht duty, obligation; (v.) Middle English plighten, Old English plihtan (derivative of the noun) to endanger, risk, pledge; cognate with Old High German phlichten to engage oneself, Middle Dutch plihten to guarantee

The verb plight “to bind (someone) by a pledge, especially of marriage” comes from Old English plihtan “to endanger, compromise, be in peril of, put under risk of forfeiture, pledge.” The connection between promising to marry someone and being in peril isn’t immediately apparent. When this word first appeared in Old English as plihtan, it was with the sense “to endanger or compromise (life, honor, etc.).” It later came to mean “to put something in danger by risking its forfeiture,” which is where “pledge” comes in. If one makes a pledge, one has the solemn duty to fulfill it, at the risk (or peril) of losing one’s honor. This may be an oath you make to a king, or a vow you make to your betrothed.
Germanic cognates of plight include Old Frisian plichta “to hand over possession of,” Middle Dutch plichten “to pledge, commit,” Dutch verplichten “to oblige,” and German verpflichten “to oblige, pledge.”