Thus she has been exploring the "new fact" that while copulation-procreation used to go together, there could now be reproductive infidelityconsidered separately from copulative infidelity.
E.g. a husband inseminating a lot of women, while not having intercourse with any of them. Or a wife going to a 'clinic" and getting pregnant outside of marital unity.
Dr. Janet smith is well-worth reading, if you want to look into it. You're a person with education as well as insight, and would appreciate her depth, I think.
While procreation (used to) require sex and all procreation was a result of sex, not all sex results in procreation.
The charge of adultery or fornication exists as a result of the sex act itself whether or not procreation is involved.
So God impregnating Mary is not open to the charge of adultery or fornication because no sex, no one flesh union, occurred between them.
Since God does not sin, God could impregnate her without sinning, whether human minds want to believe that or not.
Scripture tells us that Joseph waited until Mary delivered Jesus to have sex with her, and goes on to tell us the names of Jesus’ brothers.
It’s very clear that Mary did not remain a virgin after the prophecy was fulfilled and that does NOT diminish the role she played or her as a person.