The pair wed in London last year (12), and now Melua has revealed she fell for him after he made it clear he understood how devoted she was to her career.
The star credits Toseland with helping her overcome a "crash" in her life by being supportive of her work.
She tells Britain's The Sun, "There was a crash. The biggest thing I learned was that I was a human being and that I'm not able to go without sleep and handle loads of work pressure and pressure at home.
"Now everything's a hell of a lot easier than it was before 2010. James has been an incredible support. Marriage has changed me massively. There are so many factors. It's been amazing to know someone who's had a similar lifestyle to me and who's had a similar journey. He grew up on caravan sites and from the age of 15 or 16 he became a pro motorcycle racer.
"One of the first times when I knew I wanted to spend the rest of my life with him was because he completely got my obsession with work and music and he said, 'I know what it's like to have a job that you would kill for and would do anything for.' Before that, I had a few relationships where it had been an issue."