en_tn/deu/20/07.md

What man is there who is engaged to marry a woman ... Let him go home

"If any soldier here has promised to marry a woman, but has not yet married her, he should go back to his house"

so that he does not die in battle and another man marries her

The officer is describing a situation that could possibly happen to a soldier. Alternate translation: "so that, if he dies in battle, another man does not marry her instead of him" (See: rc://en/ta/man/translate/figs-hypo)