And at that moment Pierre felt that Helene not only could, but must, be his wife, and that it could not be otherwise.

He knew this at that moment as surely as if he had been standing at the altar with her.

How and when this would be he did not know, he did not even know if it would be a good thing (he even felt, he knew not why, that it would be a bad thing), but he knew it would happen.