Based on truth?

I just saw this movie again and I still love it! As other people have noted it covers so many topics without hitting you over the head with them. I also agree with whoever wrote that never did Elvis look better! I was never really an Elvis fan as far as looks go; he was a great lookiing-no doubt but just not my type. But in this movie, hubba-hubba! Maybe because he was playing someone relatable and who fell for the regular girl.
But anyway I digress. I wondered if this story was loosely based on Elvis' romance with Dolores Hart the actress who went on to become a nun. And no she didn't leave the order for Elvis so for all of you who think that MTM left the order, mmmmmmmm, maybe not!