Why did Bristol Palin call off wedding at last minute?

Did Bristol Palin get cold feet or is there another reason behind her decision to call off her planned weekend wedding to U.S. Medal of Honor recipient Dakota Meyer?
Former Alaska Gov. Sarah Palin, the mother of the almost bride-to-be, announced Monday on Facebook that the wedding is off.
"Bristol and Dakota couldn't be more thankful for the love and support of family and friends over the past months while preparing for their wedding," Palin wrote. "They have informed loved ones that unfortunately the announced celebration planned for May 23 will not be held."
No reason was given for canceling the nuptials. But Palin also included a note from her daughter, dismissing recent allegations that Meyer had never secured a divorce from a secret marriage.
"Regarding salacious headlines in recent days about 'secret wives,' Dakota and I discussed our past relationships prior to our engagement," Bristol wrote via her mother's post. "Dakota was legally divorced years ago, as any good reporter could and should have disclosed to readers. As usual, false stories and dramaticallywritten headlines begging controversy should be disregarded, and we have faith that our privacy will be respected at this time by those with decency."
The elder Palin also included a photo of a poster that reads, "Trust in God's timing. It's better to wait awhile and have things fall into place than to rush and have things fall apart."
"Rush" seemed to be the right word to describe the whirlwind engagement, which the couple announced in March, USA Today reports.

In addition to being Palin's daughter, Bristol is well known for her third-place finish on "Dancing With the Stars" and for starring in the Lifetime reality show, "Bristol Palin: Life's a Tripp."