One was reported in San Francisco a few years ago, and I know of one in Canada. But Willy Bill probably won't marry one. However, the overarching aspect of marriage, the one that ought to be part of the dictionary definition, is that Sally will get the children. She'll get the house too, but the world is full of houses. The kids are the killer.
Women have a mysterious power to fog men's minds.
Even if it happened, we'd still be friends. There was a case of this reported too. In central China. Scholars debate its authenticity. Willy Bill very likely will get divorced, which will very likely be Sally's idea, and she will get the kids with virtual certainty.