A thousand-mile marriage fate is drawn together by a single thread.
Tips
culture
Chinese folklore says the 月下老人 ('Old Man Under the Moon') ties an invisible red thread between fated couples, even across great distance, making 姻缘 a bond chosen by fate, not by the individuals.
memory
姻 (marriage by relation) + 缘 (fate/affinity) together mean 'fated marriage.' The same 缘 appears in 缘分 (fated connection).