The former Disney actress got engaged to Christopher in August, after just eight months of dating, but claims she had an instant feeling that he would be her future hubby.
Speaking in a radio interview with Ryan Seacrest recently, Ashley said: "I think from the moment that him and I met, I just knew it. I was like, 'Ok this is the guy,' and he knew the same thing. It doesn't get any better. I just can't explain it."
The 28-year-old songstress also insisted to Ryan that she wouldn't have got engaged so soon, if she hadn't been sure about her future with rocker Chris.
"I've obviously been in long relationships in the past," she added. "But I think because of knowing what I wanted, I wouldn't have gone into a relationship if it wasn't what I wanted.
"It's all natural between us. With other relationships you're just kind of trying too much to make it work."
Chris proposed to Ashley on top of the Empire State Building over the summer, during a loved-up trip to New York.
That same evening, Ashley tweeted: "Best night of my life. We're on top of the world."
Earlier this year, Ashley's grandfather sadly passed away and this difficult experience inspired her to begin recording music again - for the first time since 2009.
And music producer Chris was right by her side and on hand to assist with the songwriting.
The couple have made a handful of public appearances together over the last few months and look head over heels for each other in every photo we've seen.
No word yet on when the big day will be, but we bet Ashley's already started planning!
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