The barrister Stryver tells his junior, Sydney Carton, that he wants to marry Lucie Manette. He isn't in love with Lucie; he just thinks that, as his wife, she will make a nice home for him. Stryver's view of marriage is strictly instrumental; emotions don't enter into it. So long as he ends up with a charming little wife at home, he'll be perfectly happy.
As very much a man of his time, Stryver doesn't stop to consider for one moment how Lucie might feel about all of this. He blithely assumes that she'll marry Stryver out of gratitude for getting Charles Darnay off the hook. (Though it was really Carton, as always, who did all the work.) Darnay, on the other hand, has a completely different attitude towards marriage. He wants to marry Lucie because he loves her, because he has genuine feelings for her.