This is my fourth book, and it's still fanfiction. I started writing it even earlier than Princess of Light, but I stopped updating Gundam Twins because I wanted to write a book that could get a contract.
After Princess of Light failed to get a contract, I finally published this book about Gundam, which I wrote back in 2011. Another reason was that when I couldn't keep writing Princess of Light, maybe trying a different approach would help me relax.
As it turned out, it only gave me another book to keep updating.
As for why this Gundam story ended with the protagonist getting married, that has to do with the author's own experiences.