I have left a few comments there, but I think a fuller response is merited...
The Problem:My answer to this was, and remains, SURE! A bishop has jurisdiction over his diocese and everything which takes place, as it relates to the Church comes under his authority within his jurisdiction. Eastern Catholics who have migrated to Western territories have to understand that the bishop of the territory they have moved to has the authority over that diocese.
The normative Roman Catholic position is that only single men can be ordained to the priesthood. Likewise, the Orthodox have celibate clergy, but they are usually required to take monastic orders, to fill the family void. However, Orthodox Bishops will also ordain married men to the priesthood. (Neither Church allows single men who have been ordained to later marry.) In a reunited Church, could Orthodox and Catholic parishes live side by side with people possibly transferring between parishes, one ordaining married men to the priesthood and one limiting it only to unmarried, single men?
Another reason the Eastern Catholic discipline of a married priesthood is relatively unknown is because it is generally restricted to the traditional homelands of these Eastern Catholic Churches.And one would expect that the traditions of the homeland remain in the homeland! Why would an Eastern Catholic presume that just because they had traditions back home that these traditions are to be automatically accepted by Western Catholics? Likewise, the Sacraments of Marriage, Confession and Confirmation are all under the auspices of the local ordinary (bishop) and a Western bishop in an Eastern jurisdiction should not presume to authorize these without consent of the Eastern bishop.
For an example of a Latin Rite practice (one which I personally oppose and do not participate in) is communion in the hand. What would the Eastern Rite priest think if a Latin Rite person were to reach for the spoon? Of course that would be expressly forbidden! I have witnessed some Latin Rite Catholics who "self-intinct" by taking communion in the hand and then approaching the Chalice they take the Host and dip it - this practice is expressly denied in the GIRM (#287). It is possible for a Latin Rite priest to practice intinction, but it would be quite illicit for a communicant to self-intinct.
Vatican II issued the Decree of the Catholic Churches of the Eastern Rite wherein it states:
The Catholic Church holds in high esteem the institutions, liturgical rites, ecclesiastical traditions and the established standards of the Christian life of the Eastern Churches, for in them, distinguished as they are for their venerable antiquity, there remains conspicuous the tradition that has been handed down from the Apostles through the Fathers and that forms part of the divinely revealed and undivided heritage of the universal Church.It must be noted, BOTH traditions are seen as apostolic in nature - and must be respected by each rite.
The Council of Trullo, 692ad (though arguments are made that this council was a continuation of the Sixth Synod, it was not represented by the Latin Church at all and when the decrees were sent to the Pope, he would have nothing to do with them) in Canon 13 states:
Since we know it to be handed down as a rule of the Roman Church that those who are deemed worthy to be advanced to the diaconate or presbyterate should promise no longer to cohabit with their wives, we, preserving the ancient rule and apostolic perfection and order, will that the lawful marriages of men who are in holy orders be from this time forward firm, by no means dissolving their union with their wives nor depriving them of their mutual intercourse at a convenient time.My friend is not alone here:
Catholic Exchange presents this article which echoes the sentiments of my friend.
“My request is that the patriarch be granted personal jurisdiction over the faithful of his church wherever they might be,” he said (Coptic Bishop Antonios Aziz Mina of Guizeh, Egypt).
Now while echoing my friend's sentiments, it also brings out the point I have made:
With all due respect to Bishop Aziz Mina, it makes sense that a Catholic living outside their homeland to expect to be under the local jurisdiction of the bishop under whom they are living.At present, many Eastern Catholics living outside of their home territories are under the care of Latin Rite Bishops unless an Eastern Catholic hierarchy has been set up.
Note, if "an Eastern Catholic hierarchy" is established - then it is possible for the Eastern bishop to practice the traditions of their homeland without hindrance. Again, this makes sense! If there are enough of a given Eastern ethnicity in a given region, then an Eastern Catholic hierarchy can be and even should be set up. Then proper and due respect is owed to both hierarchies within a given region.
We must also point out that the practice of the celibate priesthood in the West is a discipline, not a dogma, and one that is even observed by some Eastern Rites. The discipline COULD be changed allowing for married clergy from any rite. At present the Latin Rite chooses to adhere to St. Paul's recommendation in 1 Corinthians 7:28 and especially Jesus Christ Himself in Matthew 19:11-12:
- He answered, "Not all can accept [this] word, 8 but only those to whom that is granted. Some are incapable of marriage because they were born so; some, because they were made so by others; some, because they have renounced marriage 9 for the sake of the kingdom of heaven. Whoever can accept this ought to accept it."
8  [This] word: probably the disciples' "it is better not to marry" (Matthew 19:10). Jesus agrees but says that celibacy is not for all but only for those to whom that is granted by God. 9  Incapable of marriage: literally, "eunuchs." Three classes are mentioned, eunuchs from birth, eunuchs by castration, and those who have voluntarily renounced marriage (literally, "have made themselves eunuchs") for the sake of the kingdom, i.e., to devote themselves entirely to its service. Some scholars take the last class to be those who have been divorced by their spouses and have refused to enter another marriage. But it is more likely that it is rather those who have chosen never to marry, since that suits better the optional nature of the decision: whoever can . . . ought to accept it.
Jesus Himself recommends celibacy for those who are called to it, and in the Latin Church, those who are called to celibacy are also called to serve Him in His Church. There are places for the married too, up to and including the deaconate, so married individuals are not forbidden from serving Him through His Church - they would just do a different role within the Church.
So, to answer my friend's question, "Can East and West co-exist with married and unmarried priests?" The answer is YES! So long as the local ordinary and the disciplines for each jurisdiction are respected on BOTH sides, then most certainly we can co-exist. It seems to me that those bringing up married v. unmarried clergy are actually either deliberately or subconsciously throwing up road blocks, or attempted ones at least, in an attempt to thwart reconciliation between the East and the West. Again I wish to emphasize that if proper respect is given on BOTH sides - this is really a non-issue, or a mountain from a molehill.