Beginning of the end
Jack didn’t even have the common courtesy to talk to her in person about it, this is what hurts the most. In addition, he began his letter by addressing her as his wife and then ended the letter by telling her he no longer loved her.
The end of a marriage
Laura had no idea that Jack was feeling this way at all. She felt that the announcement came out of nowhere. She started to blame herself for how terrible their communication has been because she wasn’t aware that things were already falling apart and she was oblivious to it all.