In the Orthodox Church the sacrament of Holy Matrimony is seen as an ascetic discipline. Matrimony is one of the two paths given and sanctified by the Church as a means of working out one’s salvation; the other is monasticism. Holy Matrimony is a mystical image of the union of Christ and the Church, and thus conveys the experience of being united in Christ to another person by the grace of the Holy Spirit, and thus, the life of the Kingdom of God. Grace, which is the life of God poured out on creation, is nothing other than His Love. Marriage is an ascetic discipline because it has as one of its major purposes to bring people to maturity, emotional and spiritual, by teaching mutual self-renunciation and self-denial, in order to overcome selfishness. This goal of overcoming selfishness is the foundation of spiritual life and growth, and enables the couple to live in communion with God and one another. To overcome selfishness is to be able to authentically love and be loved.
It should go without saying that the Orthodox Church does not conceive of marriage other than between a man and a woman.