Dear Jim:

I have moved your question to the Faith and Spirituality Forum as your question is less about Liturgical Law than it is about moral theology.

The correct answer to your question best comes from moral theology.

It is highly likely that this young couple are not familiar with the law of the Church and the moral imperative regarding the Most Holy Eucharist. We should at least give them the benefit of the doubt.

As such, your wife has an obligation to kindly and gently inform the couple that they must refrain from receiving the Most Holy Eucharist until such time as their marriage is regularized in the Church, and they are able to make a good confession. It is only at that time that they are in good standing, in a state of grace, and thus eligible to receive our Lord. This the the law.

If needed, your wife can explain why this is the law.

The reason the couple cannot receive Communion is that in the eyes of God and the Church, they do not have a valid marriage. Not having a valid marriage means that while the State considers them married, God and the Church does not, meaning that the couple is living in sin — the sin of fornication (adultery, if one or both of them had previous marriages which have not be annulled) . This is a grave sin. Anyone with grave sin on their souls is ineligible to receive the Eucharist.

If someone with grave sin on their souls, which this couple does have, goes ahead and receives the Eucharist anyway, knowing that they are to refrain from receiving, then they are committing one of the worse sins in the universe; a dangerous sin.

St. Paul says of people who receive the Eucharist unworthily:

(1 Cor 11:27-30)  Whoever, therefore, eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of profaning the body and blood of the Lord. Let a man examine himself, and so eat of the bread and drink of the cup. For any one who eats and drinks without discerning the body eats and drinks judgment upon himself. That is why many of you are weak and ill, and some have died. 

To partake of the Eucharist can lead to weakness, illness, or even death. Of course, the most severe consequence of "profaning the body and blood of the Lord" is eternal damnation in hell for the unrepentant.

One is a fool who says, "I will repent later." Our Lord, Himself, warns us:

(Luke 12:19-20)  And I will say to my soul, Soul, you have ample goods laid up for many years; take your ease, eat, drink, be merry.' But God said to him, 'Fool! This night your soul is required of you; and the things you have prepared, whose will they be?'

For the sake of this couple's souls, they need to obey the Church law and the moral imperative. To purposely and knowingly commit this dastardly, which they will know when your wife discusses this with them)  sets one up to commit other sins. St. Teresa of Ávila makes this observation when she said, "The more we see failure in obedience, the stronger should be our suspicion of temptation."

These are the sorts of information that your wife can teach the couple if they need deeper explanation beyond the instruction of the basic law that they need to wait to receive the Eucharist.

If the couple refuses this instruction, then the pastor needs to be informed. After that, it is no longer the direct concern of you or your wife, other than to pray for them as they are risking hell if they do not listen to Church teaching.

God Bless,
Bro. Ignatius Mary