Praise the Lord. I read your correspondence regarding oral sex and found it to be very enlightening. Does this reasoning also apply to a woman relieving her fiancé using masturbation on him until they marry?
"Now concerning the things of which you wrote to me: It is good for a man not to touch a woman" (I Corinthians 7:1).
Unmarried couples have no business engaging in sexual acts, which includes foreplay, sexual touching, hand jobs, or mutual masturbation. See: Is foreplay wrong if it doesn't lead to sex? Your fiance is quite capable of relieving himself without your involvement. That you intend to get married is not the same as being married.
Thank you so much for your response and boldness in the Lord.