The knot itself is quite the dichotomy. Its symbolism entrenched in both the bound and the free, elements of untrustworthiness and ultimate trust, of being controlled and of pure control itself. The knot is both a symbol of restriction and a powerful bond between two people, no wonder it is used in so many cultures as a metaphor for marriage along with the eternal ring.
In terms of who was first to use the phrase no one quite knows the exact origin. In Romeo & Juliet a tying of knots in reference to marriage appears
"I'll have this knot knit up tomorrow morning."
But Shakespeare also used it metaphorically for many other purposes through out his work particularly in reference to being bound. In fact the knot was so important to him that he included it in his family crest.
There are also earlier literary reference in old English from around the middle of the 11th century.
But it is in Japan where the polarity of this metaphor is most clear. The Japanese have elevated knotting to a decorative art form. Intricate and beautiful knots have adorned the front of wedding invitations for hundreds of years on the one hand, while on the other kinbaku, a perfected and well practiced art form that translates as "beautiful bondage".