That's three times, not 4, and the 2nd and 3rd marriages are allowed only under strict conditions, with the 3rd remarriage harder to obtain than the 2nd. 4th marriage is forbidden. So no, there's no frivorce in Orthodoxy. The reason for the multiple marriage allowement is due to the application of economia in order to avoid permanently alienating people from partaking in the Eucharist and thus the church:
The Maccabees waged war even on the Sabbath back in the Old Testament in order to prevent the Judeans, from whom Jesus would eventually come, from being literally wiped off the face of the Earth by their enemies at the time. ("The Sabbath was made for man, not man for the Sabbath.")
Even after going on epic rants against the re-Judiazation of the New Covenant and how it spit on Jesus' sacrifice in his epistles, (even going so far to say that if you get a circumcision, you might as well cut the whole thing off) St. Paul the Apostle still circumcised Timothy to placate Jewish Christians, because the salvation of Timothy's soul was more important than a Pharisaical exact following of the covenant.
It is in the spirit that remarriages are allowed. The Catholic church itself at times, also utilizes annulment to deal with human weakness in problematic marriages.
Though we're probably going to have to agree to disagree, quite frankly, in terms of intentions and results, I think that the differences between non-abortive contraception (i.e. no morning after pills, etc. allowed in Orthodoxy) and Natural Family Planning as recommended by the Catholic Church, are petty.
As for Liberalization… I can only speak for my church, but I fail to see it. My congregation consists of mostly people who are politically right-wing, with a few people who are moderate/center-left at the most. (i.e no SJW shenanigans.)