love-knot
/ˈlʌvnɒt/noun
1 Figurative and in allusive use. Something that constitutes or maintains a union based on love; a tie or bond of love.
2 Literal. A complex, ornamental knot considered to be a symbol of true love and used as a love-token; a representation of such a knot.
Origin
Late Middle English; earliest use found in William Langland (c1325–c1390), poet. From love + knot.