Because marriage is only for lay people, not for clergy. Lay people who are married can then go on to become a priest (and not a bishop) and they must then devote their life to God, and not so much to their wife any more. But they cannot marry after they have taken vows to serve God, as the calling to serve God is higher than serving a wife.
The Bible tells us "He who is unmarried cares for the things of the Lord - how he may please the Lord. But he who is married cares about the things of the world - how he may please his wife." (1Corinthians 7:32-33)
Also, "...it is good for a man to remain as he is...Are you loosed from a wife? Do not seek a wife." (1Corinthians 7:26-27)
Latin Rite priests have always been celibate to more perfectly conform to the model of Our Blessed Lord, Jesus Christ, who was chaste His entire life.
Orthodox priests could marry, Catholic priests could not.
Whether or not purgatory existed.
as far as i know they share everything with the roman catholic church except priests can marry and the pope is not the head of there church
Catholicism traditionally prohibits its priests from marrying, as part of the vow of celibacy.
Catholic priests will refuse to marry anyone not belonging to their faith. A Protestant pastor will do the job.
In most Christian churches, clergy are allowed to marry. Indeed in some churches there are priests married to each other (e.g. in the Church of England there are many husband and wife clergy families). This includes most Protestant churches and the Orthodox church, where parish priests can be married but monks, bishops and above remain celibate. The largest church with celibate priests is the Roman Catholic church. In this church, it is held that celibacy helps the priest to focus on God and service to the church. However, the issue of celibacy is not a matter of faith or theology, but a vow imposed on the majority of western-rite (Latin) Roman Catholic priests. The major reason for this requirement is to prevent a conflict between family life and service to a priest's parishioners. Contrary to widely held opinion, there are, and always have been, married priests in the Catholic church. Eastern-rite Catholic priests, such as the Maronites, and, more recently, already married Anglican priests who convert to Catholicism and wish to be Catholic priests, continue to serve in the priesthood. One condition of priesthood for married former-Anglican priests is that they may not serve in the role of principal parish priest, in order to conform with the principle of celibacy imposed on the majority of Roman Catholic priests. It is worth remembering that many of the early priests of the church, including the first pope (St Peter) were married.
The Vow of celibacy is meant to help priests focus on a relationship with God, rather than a relationship with a partner; Catholic priests are an alter Christus - another Christ, they are to mirror Him in their lives, they are His representatives; they are already "married" to the Church.
Episcopal priests are allowed to marry; I have no problem with that. Perhaps the Catholic Church could allow some priests to marry--I'm not convinced that it is a bad thing. I don't make these decisions, however.
PRIESTS CAN MARRY AND HAVE A FAMILY AND A HOME
In the Roman Catholic Church, it is required that a priest be celibate. This is to keep the priest from being distracted from doing God's will as a priest. However, if an Anglican or Orthodox priest who is married converts to Catholicism he is able to become a Catholic priest and keep his wife. In the Eastern Catholic Church though, the priests are allowed to marry though. Lutheran and Episcopalian Priests are allowed to marry as well.
There can be no such person as a "wife of the Pope". The Pope must be a Cardinal of the Catholic Church. Cardinals are, for the most part Bishops (with a few priests). All priests and bishops of the Catholic church take a vow of celibacy when they are first ordained and cannot ever marry. Even in the Eastern Rites which allow married priests, the Bishops are only chosen from the celibate priests.
Then as now Catholic Priests could not marry; but Anglican Priests who were not members of religious orders were allowed to get married.