I would remember this sentence from Saint Peter
1 Peter 3
1Likewise, ye wives, be in subjection to your own husbands, that if any obey not the Word, they also may be won without the word by the conduct of their wives
According to what I understand, Orthodox can only marry at the City Hall. This is enough not be considered as FORNICATORS. The Orthodox marriage is a mystery : like all mysteries, it bestows Grace and give the Divine energy to lead a Christian life within the marriage. By the way, we must remember that the aim of marriage in Orthodox theology does not consist in not being a fornicator but in being saved because the wife and the husband help one another... That is why marriage is often compared with monasticism...
According to what I could see in a Traditionnalist jurisdiction, civilly married couples commune even if they never married in church... I prefer a faithful civilly married couple than a religiously-married couple where the husband cheats his wife...
It is true that already baptized orthodox should not marry heterodx people.