Question: Hopefully this is not a silly question. What is the meaning of the title "Closer"?
Answer: At different times, the characters were getting closer to a happy life with a committed relationship, but each of them ruined it. Larry confessed to Anna that he slept with someone during a business trip. He assumed that he could apologize and make it better. Dan and Anna had an affair, cheating on Alice and Larry. Later, Dan insisted on knowing if Alice slept with Larry. Alice was lying to Dan about her name the whole time. She was always ready to leave her current situation and disappear. All of them were close to being happy, but they insisted on having things their way.
Question: Two questions about the scene where Dan is talking to Larry online and pretending to be Anna. First, why did he want to set her up with someone if he wanted her? Also, how could he be sure that she would be at the aquarium at a certain time? I know that he knew she liked to go there, but how could he be certain that whatever guy he played the trick on would meet her there?
Answer: Dan did not know Anna would be there. This is revealed at the art exhibit when Anna tells Dan that she met Larry at the aquarium as well as their nickname for him - Cupid. He unwittingly created an obstacle for himself.
I think he had played the Internet prank/joke a few times before. He knew that Anna liked the aquarium, so if he chatted with multiple men on different days, there was a chance that Anna would actually be at the aquarium when a man arrived to meet her.
Answer: I think he set her up because he wanted to prank her for rejecting him. Just an unlucky fluke for the second part with them meeting up at the same time, I think. Or maybe 1pm is when she takes a break or gets off work at that time? Who knows. It happened, though.
Answer: My theory is that Dan was trying to create a bunch of sleazy, annoying encounters for Anna to deal with. As another comment says, he probably did this several times, knowing that she liked the aquarium. He thought she would finally give him a chance after dealing with those men from the chat rooms. But it backfired—he actually helped her meet a future husband.
Answer: No such thing as a silly question. The title refers to the central theme of the film and the play upon which it is based: Knowing the truth doesn't bring us closer together. It is meant to be ironic, truth offers clarity but actually drives people further apart.
BaconIsMyBFF
This makes sense. Dan insisted on knowing if Anna had sex with Larry, when she met with Larry to discuss the divorce. Later on, Dan kept asking Alice if she slept with Larry. Neither truth made him happier.