Could someone please explain these puzzling plot questions? (SPOILERS)

I was under the impression that Garrett wrote the messages in the bottle after his wife died and was working out his grief by sharing things with her that he failed to convey when she was alive. But the story later seems to (maybe) suggest that she was still alive when he wrote the messages, albeit sick and dying in their home.

Over two years after her death, when Garrett's visiting Theresa in Chicago, he discovers his messages to Catherine in a drawer and finds out that there was a third message in a bottle from the same paper & typewriter, which turns out to be from Catherine to him.

Does this mean Garrett wrote the two messages and put them in a bottle while Catherine was still alive while deathly ill in their home? If so, why did Garrett put the typed messages in a bottle and throw them into the ocean? After all, she was still alive and therefore he could simply convey these heartfelt things to her face-to-face rather than waste them on the ocean.

Then there's the issue of Catherine: Why would she type a message for Garrett put it into a bottle and throw it into the ocean? Why not just communicate with him in person? Throwing the message into the sea would almost guarantee that he'd never read it. Then there's the further problem of the deathly ill Catherine walking down to the ocean and throwing a message in a bottle into it (which would have to be at a strategic point where the tide would surely take it out to sea).

One possible explanation is that Garrett wrote the first two messages after his wife died while the third message found & faxed to the Chicago Tribune was Catherine's message which she wrote just before she died and was able to throw it into the ocean before passing away. But this doesn't clear up the issue of why she didn't just tell Garrett these things in person before she died, especially since -- once the message was thrown into the ocean -- it was highly unlikely that Garrett would ever be able to read it.

Another issue is the unlikeliness that Catherine would get this idea to write a message to her husband, put it in a bottle and throw it into the sea and then, after her death, Garrett would be inspired to do the very same thing. Why Sure!

I'm sure the book doesn't have these perplexing issues and that the scriptwriters fudged it up in translation. For instance, I heard the book didn't feature Catherine writing a message in the bottle to Garrett.