How often does a non-paternal adult get custody of a child in a divorce when both birth parents are still alive?
Putting the weird triangle relationship aside, where does the biological father fit in? I bet this will be the big question in the child’s early adult life. Was the father a sperm bank doner? Was it a one night stand? Will the child know about genetic risks. The biological mother is the one that created this mess because of selfish desires.
The ‘birth father’ was a sperm donor, so no dice there... however, the other birth parent is still alive and married to a person of the opposite sex, which means that there will hopefully be a somewhat stable environment for the child.
Also, this isn’t about ‘custody’, this is about ‘parental rights’ which include custodial rights, but also visitation rights, rights to act as the child’s legal parent/guardian figure, and the ability to claim them on your taxes among other things.
And, it happens all the time in this country - as someone else posted, scenarios like this are quite common with a mother and child where the mother marries a man, husband adopts the child and gets the same rights as a biological father would have, then the mother leaves her husband for another man and a similar battle, but with a man vs. a married couple rather than a woman vs. a married couple, ensues.