"Therefore shall a man leave his father and his mother, and shall cleave unto his wife: and they shall be one flesh." —Genesis 2:4
"Since a woman’s body is a passive and receptive element, it is clear that her body collects and stores more of the results of the sexual acts than all of those men who commit adultery with her; those results are atomic substances from the men with whom she has had sexual intercourse. Therefore, when someone has sexual intercourse with a person who has been with another partner or other partners, both then absorb the atomic essences of the other partners and poison themselves with them. This is a very grave problem for those brothers and sisters who are dissolving the “I” because then, not only do they have to fight against their own errors and defects, but moreover, they have to fight against the errors and defects of those other partners with whom they had sexual intercourse." —Samael Aun Weor, The Perfect Matrimony
It is easy to misinterpret passages like this, so let us analyze it.
When you enter the psychological environment of another person, you are influenced by it. For example, if you spend time with people who drink, smoke, curse, and talk about negative things, you will be tempted to join in all of their behaviors. Naturally, if you already have weaknesses in those areas, you will be more susceptible.
Sexual union is also a joining of psychological environments, but the influences are far stronger and deeper. Observe how after being married for many years a man and woman even look alike. They talk alike, walk alike, think alike. They have truly "merged" not only physically but psychically. This demonstrates the psychological aspect of sex.
When you sexually unite with a person, there is a permanent and irreversible bond created because there is an atomic exchange, a merging of atomic substances. The bodies, hearts, and minds are united atomically. They influence each other very deeply.
So, when you sexually unite with a person, there is an exchange of psychological influences. Each sexual act of that couple reinforces the influences.
Thus, the interests, tastes, tendencies of each person are exposed to the other. So, similar to spending time with friends, but far, far deeper. Afterwards, you have a whole new set of psychological influences in your mindstream. If before you had no interest in alcohol, you now have it. That is not an "ego," but a tempting influence, that if followed, will create egos and karma.
Therefore, if you have had many sexual encounters, you have absorbed many psychological influences, and if you have acted on them, then you have created egos and karma through your own actions. That is why the passage says:
"...This is a very grave problem for those brothers and sisters who are dissolving the “I” because then, not only do they have to fight against their own errors and defects, but moreover, they have to fight against the errors and defects of those other partners with whom they had sexual intercourse." —Samael Aun Weor, The Perfect Matrimony
Those "errors and defects" are the temptations, desires, interests, tendencies, behaviors, which if acted upon, will create egos and karma.
It is impossible to exchange "egos" or "karma," because those are made by our own hands.
Your karma is the result of your previous actions. You cannot be rewarded or punished for the actions of another. Karma is exact. It corresponds to your own actions. Therefore, it is impossible to "absorb the karma of someone else."
"Once you have committed an action, you will experience its effect, and you will not experience the effects of what others have done." —Samadhiraja-sutra
"One does not meet with the effects of what one has not done." —Visesa-stava
Similarly, your egos are "karmic," because you made them. An ego is a psychological entity that traps your own consciousness because of your own actions. You cannot have the consciousness of another person trapped inside of you. Each ego or defect belongs only to the one who made it. Therefore, it is impossible to "absorb the egos of someone else."
This knowledge naturally leads us to become more selective in choosing our sexual partner. That is wise: we may be very particular in selecting our food, drink, clothing, or career, yet we should be the most demanding and careful in the selection of our mate. Yet, the ultimate answer to the choice of mate is not answered by analyzing the egos or karma of the potential spouse! It is answered by finding the one you LOVE. Remember: the partner of Jesus was a prostitute. He did not choose her because of karmic convenience, but because of LOVE. We ourselves are not perfect or pure. If we ourselves want understanding, acceptance, and forgiveness, then we should be understanding of the defects and mistakes of others, especially the one we love the most: our spouse.
"And Jesus, the compassionate, answered and said unto Mary [Magdalene, the repented prostitute]: “Mary, thou blessed one, whom I will perfect in all mysteries of those of the height, discourse in openness, thou, whose heart is raised to the kingdom of heaven more than all thy brethren.” —The Pistis Sophia