The full account of this lifetime is told in the Maha-Ummagga Jataka (#546), while the Amaradevi-Panha Jataka only relates this single incident from that story.
The Bodhisatta was once a king’s advisor. When he turned sixteen, he went out to find a wife. He saw a beautiful woman, named Amara, with all the marks of good luck, walking down the road, and when they saw each other, they fell instantly in love. She answered all his questions with riddles, which he solved easily. Pleased that she was as smart as she was beautiful, the Bodhisatta said he wanted to visit her family, and she told him where they lived with the Secret Path Riddle: “By way of cakes and gruel, and the double-leaf tree in flower, by the eating hand, not the not-eating hand, this is the secret path to my home.” The Bodhisatta walked past a cake shop, a rice gruel shop, and a blooming Mountain Ebony tree, then turned right and found her home.
In the Lifetime of the Buddha
One day some of the Buddha’s disciples were discussing his supreme wisdom; in particular, how he had humbled and converted a vast multitude of brahmins, ascetics, thieves, goblins, gods, and more. When the Buddha heard them talking about it, he told them this story so they knew that he’d also had perfect knowledge in the past.
Amara was an earlier birth of the Buddha’s wife.