This reading was added to the last Lectionary revision. If you have an old marriage prep booklet, it’s likely not included. This reading, by the way, is mentioned by a correspondent to Zenit’s Liturgy Q&A column this past week.
I believe all English-speaking countries include this in the official Lectionary and with an approved translation. If you don’t see it, you’ll likely wait for the new edition of Roman Missal III. Most churches aren’t buying liturgy books these days.
The text of the reading comes from the final chapter of the Hebrews. It’s a final word of encouragement to its listeners/readers. I wonder if its inclusion for the wedding liturgy is more for the reference to marriage and the marriage bed.
Brothers and sisters:
Let mutual love continue.
Do not neglect hospitality,
for through it some have unknowingly entertained angels.
Be mindful of prisoners as if sharing their imprisonment,
and of the ill-treated as of yourselves,
for you also are in the body.
Let marriage be honored among all
and the marriage bed be kept undefiled.
Let your life be free from love of money
but be content with what you have,
for he has said, I will never forsake you or abandon you.
Thus we may say with confidence:
The Lord is my helper,
and I will not be afraid.
I hope this passage hasn’t been cherry-picked from a concordance, for the general advice is quite appropriate. Honoring marriage and sex is among the qualities raised up for the domestic church. Sex isn’t at the pinnacle.
Are you wondering about the half-verse that was excluded? It’s a revision to keep things positive, for the text reads, “for God will judge the immoral and adulterers.” Assess for yourself if that would be a distraction for your wedding guests, and why it was likely left out.
Loving a spouse does not mean the exclusion of affection, regard, and friendship within the Christian community, or indeed, with any other person. As a sacramental sign for the world, marriage needs couples practicing hospitality in their home. How else is married life better witnessed?