I took away from reading Theology of the Body for Beginners, which is a entry-level explanation of Pope John Paul's Theology of the Body talks aimed primarily at married couples or those interested in Catholic teaching on sexuality, that Adam and Eve could have had some great sex in the garden of Eden. I may have been misreading it or reading between the lines, but that's the gist my wife and I got.
In any event, that is not original sin, the way men and women use each other for sex and with sex is a 'fruit' of original sin. But in that sense, fruit is just something that comes from somewhere else like Jesus is the Fruit of Mary's womb or your underwear are the Fruit of the Loom.
The forbidden fruit can certainly be allegorically interpreted, but there's no reason to think it has anything to do with sex, other than to make it shameful somehow. Previous to eating of the tree, man only knew good and only sought the good. Afterwords man knows sin. Sex in and of itself is not sinful. Pope Paul VI's Encyclical Humanae Vitae (On human life) says that it's part of your vocation as a married couple.
In humble obedience then to her voice, let Christian husbands and wives be mindful of their vocation to the Christian life, a vocation which, deriving from their Baptism, has been confirmed anew and made more explicit by the Sacrament of Matrimony. For by this sacrament they are strengthened and, one might almost say, consecrated to the faithful fulfillment of their duties. Thus will they realize to the full their calling and bear witness as becomes them, to Christ before the world. For the Lord has entrusted to them the task of making visible to men and women the holiness and joy of the law which united inseparably their love for one another and the cooperation they give to God's love, God who is the Author of human life.
It's not original sin, it's obedience to your calling (not being a misogynistic guy here, being chaste for a time is also obedience to your calling).
Original sin was disobedience because of pride, the disordered desire to be like God without being obedient to Him.
Three things to ask your husband when he thinks he's so smart:
How long were Adam and Eve in the Garden?
Where was Adam when Eve ate the apple?
How big was the snake?