It's not really that Lucie's marriage foreshadows anything--except, perhaps, a very sad Sydney Carton. Her marriage is going to happen in the morning, and something is foreshadowed in those preceding hours: the setback of her father, Dr. Manette, after she leaves.
In chapter 17, on the night before the wedding while looking at the moon, Lucie and her father were talking; she felt the need to reassure her dad that their closeness would not change because of her marriage. He believes her wholeheartedly and tells her of the times in prison when he saw the same full moon, counted the number of prison bars he could see while looking at it, and pondered all he had lost. He seems to go back to that time, though not to the same degree as when he reverts to making shoes.
"'It was twenty either way, I remember, and the twentieth was difficult to squeeze in.'"
He goes on to tell of the tortured thoughts of what had become of the baby his wife was carrying when he was abducted and taken to prison. On some moonlit nights he imagined a daughter who lived a full life but had no clue he existed. On others he was released from prison by that same unknown child. On still others he was free and welcomed lovingly into the home of his own dear child--and her children had been told of him with love. He had not been forgotten.
"The time came for him to bid Lucie good nght, and they separated. But, in the stillness of the third hour of the morning, Lucie came downstairs again, and stole into his room: not free from unshaped fears beforehand."
Lucie is concerned enough to literally go check on him. He was sleeping soundly, and she pondered his face with a loving eye.
"Into his handsome face the bitter waters of captivity had worn; but, he covered up their tracks with a determination so strong, that he held the mastery of them even in his sleep."
That mastery, however, is short-lived. As soon as Lucie and Charles drive away after the wedding, Dr. Manette goes back to making shoes--as foreshadowed by all his talk of prison the night before.