Regarding the Verse:--"If a woman fears cruelty or desertion on her husband's part." (4.128) It is about a man who has a woman (wife) and he does not like her and wants to divorce her but she says to him, "I make you free as regards myself." So this Verse was revealed in this connection.
Sahih al-Bukhari, Vol. 6, Book of Prophetic Commentary on the Qur'an, Hadith 125
Sahih al-Bukhari, Book of Prophetic Commentary on the Qur'an, Hadith 125