What about the situation of a first marriage that was not documented in court, and the husband has been missing since 2012, and what is the legitimate ruling on accepting a marriage proposal from another man?

The fundamental principle is the persistence of the marriage, as per the jurisprudential rule: "Certainty is not removed by doubt." Accordingly, the marital bond remains and is not dissolved merely by the husband's absence. Rather, the wife remains under his marital authority until a Sharia judge decrees separation.

Therefore, the matter must be referred to a Sharia court, or its equivalent, to establish the marriage. It is not permissible for her to marry another man before a judgment of separation is issued and the waiting period ('iddah) has expired, based on His (Allah's) saying, the Most High: "And [also forbidden are] married women" [Quran 4:24].