Traditionally, the left ring finger is the one associated with relationships. This custom is deeply rooted in history and symbolism, particularly in Western cultures. It's believed to have originated from the ancient Romans, who believed the vein in the fourth finger of the left hand, known as the "vena amoris" (vein of love), ran directly to the heart.
However, it's important to note that this tradition can vary across cultures and individuals. Some people choose to wear their engagement or wedding rings on the right ring finger, or even on a different finger altogether. Ultimately, the meaning of the ring finger in a relationship is personal and can depend on individual preferences and cultural norms.