Should Darnay have kept his name and identity secret from his wife and not told her of his trip?This can be found in Chapter 24 of Book 2 from A Tale of Two Cities.
Darnay's decision to tell Dr. Manette of his true name and identity but not to his wife shows the prevailing attitude toward the emotional strength of women at the time. He was trying to save her from mental anguish, which she might have actually suffered, considering the prevailing attitude of women of the class toward their own emotional strength. Yet, considering what she was able to bear concerning her father, Lucie may have very well been able to bear up under this burden.
As far as keeping his trip to France a secret, again Darnay was trying to protect her. With a great deal of naivete he believed that he could slip into France, help his servant, and slip back out with no one the wiser. However, considering the circumstances, not informing her was the worst possible route to take. Her discovery of his trip only dragged her into danger when she followed him to France. By informing her of his intentions, he could have made sure that she did not follow, but trust him as much as possible on his mission of mercy.