Explanation of AT-TAHRIM verse 1 (66:1)

Verse 66:1 from Sahih International : > "O Prophet, why do you prohibit [yourself from] what Allah has made > lawful for you, seeking the approval of your wives? And Allah is > Forgiving and Merciful." I want to understand meaning of this verse. What did Prophet prohibit himself from? And cant we promise something to ourselves like I will not eat meat? Can't we promise something to our wives to protect our marriage? If possible please add which event happened before this verse sent to Prophet?