Love is a burning thing,
can change into a firy ring.
Bound for wild desire
I fell into a ring of fire.
In this first verse, the protagonist describes what love is like, describing the feeling of desire as if you yourself were on fire.
June Carter wrote Ring of Fire early on in her relationship with Johnny Cash, while they were both married to others. It was a tough time for her because she was already married, and because she knew the kind of person Cash was, even as she was falling in love with him. She once wrote this about the song:
There is no way to be in that kind of hell, no way to extinguish a flame that burns, burns, burns.
Johnny Cash compared love to a ring of fire, saying they both excite and torment the victim. The longer you stay in the relationship, the more intense the flames and the love affair becomes.
June Carter - 1963: