Isaiah sees Zion as a grieving “widow” (Isaiah 54:4). But Yahweh is her husband. Yahweh must have died if she is left in her widowhood.
Then he comes back as her ba’al (54:5), her lord and husband, making her a Lady, a be’ulah (54:1). This isn’t merely a separation and reconciliation. It is a death and resurrection.
When He returns to her, Yahweh comes as her “redeemer,” her go’el (vv. 5, 8), the one charged with responsibility to raise up children for a dead brother (Deuteronomy 25:5-10; cf. Ruth 4:1, 6, 8).
Yahweh does double-duty: He is the first Husband, who dies and leaves Zion a widow; and He is the near kinsman, the brother to the first husband, who takes grieving Zion into His keeping and fills her house with children.