I…That would leave the Roman Catholic and Orthodox faiths, and a decision between those two has been rattling in my head and going through a variety of ups and downs for over five months now. … I have confirmed with the deacon at the nearest Eastern Catholic church (Melkite) in Nebraska that our family’s attendance at an Orthodox liturgy fulfills Sunday mass obligation, due to a dispensation that is in place for those who find a true spiritual advantage in Eastern liturgies but who cannot reasonably make it to Eastern Catholic churches…
Catholics (east or west) are only obliged to assist in a Catholic ritual Church (there are 23). If this is is morally impossible, there is no obligation for the Mass or Divine Liturgy. Catholics are never required to attend a non-Catholic Church. (Our Lady’s Immaculate Heart in Ankeny is likely to be your wife’s proper parish if she is a Latin Catholic.) The Melkites have different canon law (CCEO) than the Latin Church. The canons apply to the faithful based upon their church of canonical enrollment (by adult baptism if not baptized as an infant in which case, of the Catholic parent or guardian that raised them in the faith).
Latin Canon Law (CIC) Can. 1 The canons of this Code regard only the Latin Church.
Can. 1248
§1. A person who assists at a Mass celebrated anywhere in a Catholic rite either on the feast day itself or in the evening of the preceding day satisfies the obligation of participating in the Mass.
§2. If participation in the eucharistic celebration becomes impossible because of the absence of a sacred minister or for another grave cause, it is strongly recommended that the faithful take part in a liturgy of the word if such a liturgy is celebrated in a parish church or other sacred place according to the prescripts of the diocesan bishop or that they devote themselves to prayer for a suitable time alone, as a family, or, as the occasion permits, in groups of families.
Eastern Canon Law (CCEO) Canon 1
The canons of this Code affect all and solely the Eastern Catholic Churches, unless, with regard to relations with the Latin Church, it is expressly stated otherwise.
Canon 881
- The Christian faithful are bound by the obligation to participate on Sundays and feast days in the Divine Liturgy, or according to the prescriptions or legitimate customs of their own Church sui iuris, in the celebration of the divine praises.
- In order for the Christian faithful to fulfill this obligation more easily, the available time runs from the evening of the vigil until the end of the Sunday or feast day.
- The Christian faithful are strongly recommended to receive the Divine Eucharist on these days and indeed more frequently, even daily.
- The Christian faithful should abstain from those labors or business matters which impede the worship to be rendered to God, the joy which is proper to the Lord’s day, or to the proper relaxation of mind and body.
Other References:
Regarding non-Catholic liturgical participation, 118 below pertains to vespers (non-sacramental) and 115, 122, 123 to sacraments.
In 1993 was given the DIRECTORY FOR THE APPLICATION OF PRINCIPLES AND NORMS ON ECUMENISM 115. Since the celebration of the Eucharist on the Lord’s Day is the foundation and centre of the whole liturgical year, [120] Catholics—but those of Eastern Churches according to their own Law [121]—are obliged to attend Mass on that day and on days of precept. [122] It is not advisable therefore to organize ecumenical services on Sundays, and it must be remembered that even when Catholics participate in ecumenical services or in services of other Churches and ecclesial Communities, the obligation of participating at Mass on these days remains.
a) Sharing in Sacramental Life with members of the various Eastern Churches
- Between the Catholic Church and the Eastern Churches not in full communion with it, there is still a very close communion in matters of faith. [125] Moreover, “through the celebration of the Eucharist of the Lord in each of these Churches, the Church of God is built up and grows in stature” and “although separated from us, these Churches still possess true sacraments, above all—by apostolic succession—the priesthood and the Eucharist…”. [126] This offers ecclesiological and sacramental grounds, according to the understanding of the Catholic Church, for allowing and even encouraging some sharing in liturgical worship, even of the Eucharist, with these Churches, “given suitable circumstances and the approval of church authorities”. [127] It is recognized, however, that Eastern Churches, on the basis of their own ecclesiological understanding, may have more restrictive disciplines in this matter, which others should respect. Pastors should carefully instruct the faithful so that they will be clearly aware of the proper reasons for this kind of sharing in liturgical worship and of the variety of discipline which may exist in this connection.
- Whenever necessity requires or a genuine spiritual advantage suggests, and provided that the danger of error or indifferentism is avoided, it is lawful for any Catholic for whom it is physically or morally impossible to approach a Catholic minister, to receive the sacraments of penance, Eucharist and anointing of the sick from a minister of an Eastern Church.[128]
vatican.va/roman_curia/po…ectory_en.html
More details were given later in 1996 on canon 881 (see 64. Feast days):
Instruction for Applying the Liturgical Prescriptions of the Code of Canons of the Eastern Churches
byzcath.org/faith/documents/instruction.htm