In the Ten Commandments, we are told to "honor thy father and mother." If the Blessed Virgin Mary had children other than our Lord, His taking her away from them would have made it impossible for them to keep this commandment.
There are other reasons, but this is the simplest one and as I said, I am at my office.
What a stretch! Jesus did say she was being taken away from her children but that John was to look after her as his own mother and she was to consider John as a son. You are adding what is not stated again.