The NIV Study Bible strongly supports my conjecture that husbands’ proximity to constantly lactating breasts back in the day meant the inevitability of Couples Nursing. Consider 1 Samuel 1:22 and study notes:
“Hannah did not go. She said to her husband, ‘After the boy is weaned, I will take him and present him before the LORD, and he will live there always.'”
1:22 weaned. It was customary in the East to nurse children for three years or longer (in the Apocrypha, see 2 Maccabees 7:27) since there was no way to keep milk sweet.
And 2 Maccabees 7:27 states:
“27 But, leaning close to him, she spoke in their native tongue as follows, deriding the cruel tyrant: “My son, have pity on me. I carried you nine months in my womb, and nursed you for three years, and have reared you and brought you up to this point in your life, and have taken care of you.”
Therefore, bearing many children + extended breastfeeding = husband breastfeeding.