Thor has a very strong urge to write to Jane, so he does so. This letter flows much better for him.
For a long stretch of time, Odin kept Thor unnaturally busy. Thor knew that Odin disapproved of his affection for Jane. He knew that Odin wanted him to marry Sif. But, Thor cared deeply for the mortal woman, and he had given her his word that he would return for her. He would not be a liar, and he hoped that writing these letters would get her to understand a little bit once they were finally reunited. This is how Thor found himself in the privacy of his mother's chambers, where she promised him as much time as he needed to write another letter to Jane.
Dear Jane,
I'm sorry that I have not written in a while. I have been quite busy. Father has been stepping up my training in becoming King. He knows that I shall have to take over the throne soon. Not only that, but there have been uproars that are quite difficult to contain throughout the nine realms. Father tries to do his best to stop and help the other realms, but it is hard without the Bifrost to travel.
I do hope that you are well. Heimdall has told me that you are trying to build your own Bifrost. He says you call it a portal. I hope that you are successful soon, because seeing you again would bring me much joy. We have not had much joy in Asgard since the destruction of the Bifrost. If you get your portal working, I hope it can send you here. You would enjoy yourself immensely here, and I do believe that you and Mother would become great friends. Perhaps you could bring Darcy, too. Fandral often whines to me about missing my Midgardian friends, though I know he means Darcy. He did not get to talk to you the way that he did Darcy. The Warriors Three and Sif would like to see all of you again, and I would be gladdened by your presence.
Please keep yourself safe and taken care of. I do not want your health to suffer as you work. While I want nothing more than to see you again, I do want you to be in good health when I do. I hope that the time is coming close for us to see each other again soon.
Always,
Thor
Thor looked at the letter, giving it a once over. He nodded to himself. This letter flowed more easily than the first two, and for that he was grateful. It was becoming easier to write. He placed it in an envelope and marked it with the number three. He would make sure that Jane got all of his letters, and that she read them in chronological order once he returned.
"Soon, Jane," he murmured out loud.
It was a promise to himself and to her.
Aren't these letters getting better? Soon enough, he'll be writing to apologize for not seeing her while he was on Earth after the Battle of New York.