Since God made Eve from Adam's rib, is it all right if a husband is younger...
Genesis 2:21 - 23
21 And the LORD God caused a deep sleep to fall on Adam, and he slept; and He took one of his ribs, and closed up the flesh in its place. 22 Then the rib which the LORD God had taken from man He made into a woman, and He brought her to the man.
5 And there you shall build an altar to the Lord your God, an altar of stones; you shall not lift up any iron tool upon them.
9 "then his brother's wife shall come to him in the presence of the elders, remove his sandal from his foot, spit in his face, and answer and say, 'So shall it be done to the man who will not build up his brother's house.'