Well first obviously your wife did not sin. No one is obligated to receive the Eucharist at Mass. As a Catholic, one is only obligated to receive once during the Easter Season.
As well, many people have very firm beliefs about reception of Communion on the tongue (COTT) and Communion in the hand (CITH). The Norm for the universal church is COTT, and you will hear a lot of people say that while the Church permits CITH that it is still either under indult or is not the preferred practice. Since there are in the US church two valid ways to receive, your wife is not obligated at any given Mass to receive CITH if she prefers COTT.
Be careful though. You will find plenty of virtue shamers here who will pounce on your wife. They will call her names like hypocrit and holier-than-thou. They will claim that one MUST receive at all times, and that she is ‘rejecting Jesus just because she can’t have Him her way.”
The funny thing is that if these people themselves were told, “The Church in the US has revoked the Indult for CITH and you must now receive COTT” the screams and tantrums would last for years with various “rainbow parishes’ holding protests and demanding to receive CITH ‘because’.
Again, your wife is not ‘denying herself graces’ in not receiving the Eucharist at Mass. Yes, graces are available to those who receive at Mass (in a state of grace). But no, one is not REQUIRED to ‘take’ the graces, and you aren’t depriving yourself of them.
Look at it this way. There are thousands of indulgenced prayers and devotions out there, from the Liturgy of the Hours to the rosary to the Divine Mercy prayers, chaplets, litanies, etc. Every day the graces and prayers associated with all the above are ‘out there for the taking’ but no person truly has the time in a 24 hour day to pray every single prayer in the church or do every single devotion.. And in those they don’t do, they are not depriving themselves of the graces thereto.
Same with your wife. Please allow her the freedom to let her make the choice to receive or not and don’t try to pile on her if she doesn’t do what you do. It isn’t fair or right to do so. And she has done nothing wrong here.