The answer to the recent question "Why does Wemmick bring a fishing-rod on his "walk" with Pip?" explained that this was a ruse by Wemmick to conceal his wedding. My question is why this would be necessary - does Dickens give any particular reason why Wemmick should want to hide the fact that he is getting married? And from whom was he concealing it, from Jaggers, or just from the world in general?
Wemmick wanted to keep his marriage a secret because he had created two distinct personas for himself: one as a hard-nosed clerk at his job in London and the other as a loving husband and caretaker of his aging father at his home in the countryside. He believed that his coworkers at the law office would not understand or accept this side of him, and that revealing his personal life to them could jeopardize his professional reputation.
Wemmick also lived in fear of his boss, Mr. Jaggers, who had a reputation for being ruthless and unforgiving. Wemmick did not want to give Mr. Jaggers any leverage over him that could be used to control or manipulate him in the workplace.
Ultimately, Wemmick's desire for privacy and his fear of being judged or manipulated by others was what motivated him to keep his marriage a secret. It was only after he became more confident in his relationship with Pip, the novel's protagonist, that he felt comfortable sharing this part of his life with him.