When Rupa Goswami resigned his post as Dabir Khas and set out to find Sri Chaitanya Mahaprabhu, Anupama Mallika went with him. This was not simply two brothers traveling together for company: Sanatana Goswami later explained to Sri Chaitanya Mahaprabhu that Rupa and Anupama had gone toward Vrindavana specifically on the Lord's own instruction.
Their route took them first to Mathura rather than straight to Vrindavana, and there they met a poor but deeply devoted brahmana named Subuddhi Raya, who supported himself by selling dry firewood. Subuddhi Raya was overjoyed to meet the two brothers, and, knowing the district as few others did, personally showed them the twelve forests of Vrindavana - the same forests Rupa and Sanatana would spend the rest of their own lives excavating and restoring as places of pilgrimage. Anupama and Rupa stayed in the area for about a month before turning back toward Bengal to search for Sanatana, who had left separately, by a different road, and had not yet arrived.
Rupa and Anupama then continued on to Prayaga (Allahabad), where they were overjoyed to learn that Sri Chaitanya Mahaprabhu Himself was in the town, and met Him there directly (CC Madhya 19.37). It was at this meeting, in the solitary room of a Deccan brahmana's house, that Sri Chaitanya Mahaprabhu gave Rupa Goswami the extended teaching on rasa and devotional service Gaudiya Vaishnavas remember as among His most important instructions of all - with Anupama Mallika present beside his brother throughout (CC Madhya 19.45). Sanatana, still making his own way toward Vrindavana by a different road, missed his brothers at Prayaga, but word of their journey reached him anyway: when he later passed through Mathura himself, Subuddhi Raya told him everything about Rupa and Anupama's travels (CC Madhya 25.211). Sri Chaitanya Mahaprabhu later summarized the Prayaga meeting for Sanatana directly, in a single line: "I met your two brothers, Rupa and Anupama, at Prayaga. They have now gone to Vrindavana" (CC Madhya 20.66).
Learning from Sri Chaitanya Mahaprabhu that Sanatana had also set out for Vrindavana by his own road, Rupa and Anupama did not linger. They turned back toward Bengal to settle their remaining affairs with the state, intending, on the Lord's own order, to go on afterward and see Him again at Jagannatha Puri. Anupama never completed that second journey. Chaitanya-charitamrita reports what happened in a single verse, almost as spare as the news itself must have felt: "In this way the two brothers Rupa and Anupama reached Bengal, but when they arrived there Anupama died" (CC Antya 1.37). The Bengali original does not use the ordinary word for death; it says he "attained the shelter of Mother Ganges" - an idiom Krishnadasa Kaviraja Goswami's own commentary explains was used of anyone's death in that era, whether or not the person died literally on the riverbank. Tradition dates the loss to Sakabda 1436, or A.D. 1514, not long after the brothers had turned back from Prayaga.
Sanatana Goswami did not learn of his youngest brother's death until later still, at Jagannatha Puri, from Sri Chaitanya Mahaprabhu Himself - the news, and Sanatana's own remembrance of Anupama's steadfast devotion that followed it, are told in full on Tested Between Two Devotions. What the loss meant for the family beyond that one conversation was a child left fatherless in Bengal: Anupama's young son, Srila Jiva Goswami, who would grow up under his uncles' care and eventually travel to Vrindavana himself to join them. Chaitanya-charitamrita records the connection directly: "The son of Sri Vallabha, or Anupama, Srila Rupa Gosvami's younger brother, was the great learned scholar named Srila Jiva Gosvami" (CC Antya 4.227). Anupama Mallika himself never saw Vrindavana again after that one brief month with Subuddhi Raya, and never saw his son grow into the scholar he became.