On the marriage metaphor; what legal problem is the cross actually solving?

Paul says in **Romans 7:2** that *a woman is bound to her husband while he lives, but is free (to remarry) if he dies*. He applies this logic to believers and the law. Given Paul's logic, if YHWH is husband to Israel (covenant believers) at Sinai (**Jer 31:32**), divorce occurs (**Jer 3:8**), and **Deut 24:1-4** forbids remarriage to a defiled wife, **what specific legal issue does the cross address for believers?** Most Christians answer simply "*atonement for sin.*" However, does this fully address the legal question posed? Is that the full story?