There have been versions of this saying dating to the Roman times, but it’s popularity came much later. Thomas Haynes Bayly, an English poet and songwriter, used the phrase in one of his songs. In Bayly’s 1850 song The Isle of Beauty, “absence makes the heart grow founder” was the last line used. It is around this time that the saying became synonymous with lost love or, more commonly, love increasing due to being separated by distance or obstacles.
Ammer, Christine. The American Heritage Dictionary of Idioms. Boston: Houghton Mifflin Company, 1997, 2.