The article that I found, which seemed to have been done through the guidance of an adviser (Douglas G. Richards, Ph.D.) at a learning institution, (not much other info given) gives citations, dating back to the 19th century. There is probably newer research, as this article was published in 2000, and the article itself is not based on too much evidence, but I thought you might find it interesting. I don't know how I feel about this.
Most Spiritualist writers agree with Peebles (1909) that earthly marriages are for time, but soulmates are for eternity. Very few on earth find the right mate, and it may take a long time to find one's counterpart even in the spirit world. Marriage in the spirit world is for the purpose of intellectual and spiritual companionship and social interblending. There is no physical desire or contact because there is no need for procreation.
Leonard (1927) explains that two separate individuals were one before they decided to come to earth, and they will become one again, but usually after they leave the earth plane. Reuniting may take centuries in the spirit world. The perfect being has two constitutent parts, male and female, and Randall (1917) says this is not common in earthly life. All in the spirit life marry sooner or later, at which time they progress together to remain in balance.
Very few are truly married until they get to the spirit world and locate their other self or counterpart. It is the soul that marries, not the body. Peebles (1909) describes the reunited soulmates as one glorified sphere of light, but individual attributes are discernible. A reunited spirit can separate and appear as two separate individuals; there is a blending of two minds into one. Randall (1917) assures us that we will know our mates with absolute certainty, that there are no mismated couples in spirit life.
Spirits filled with mutual love can not really be separated, but they can be on different planes of development (Moses, 1949). If this happens, one is instructed and helped to grow. Loving bonds provide an incentive to mutual development, and the two help each other until progress is equal and they are one in thought and feeling. Union is forever with the soulmate. Hare (1855) says there is a greater blending of mutual love in the spirit world marriage than that of any other friendship.
Opinions vary on marriage ceremonies. Some maintain there is no ceremony, others say it can be simple and the couple can just declare their intention to friends, and still others mention that a union can be celebrated with whatever is wanted, even a festival.
Crowell (1879) answers the question of whether we meet our mates on earth in the spirit world by saying that if we are not properly mated on earth, there is no reunion. If there is spiritual affinity, families will be reunited, but if there is no attraction family members will be indifferent to each other.