I've noticed that many old (often folk) songs use the terms 'true love' together (as opposed to just 'love')? Is it to differentiate it from 'false love', due to metric or syllabic reasons, for emphasis or perhaps some other reason reason entirely?
I've also noticed that 'true love' generally refers to a person, not the abstract concept of love. Could it be out of lack for a better term to refer to one's sweetheart?
"for then, she'll be a true love of mine" - Scarborough Fair
"I sat there with my true love" - The wind that shakes the barley
"Black is the colour of my true loves hair" - Black is the colour
"I wish i sat on my true love's knee..." - Siuil a Run.