Elizabeth, 35, and Hough, 24, posted matching statements Friday through the social networking service, People.com reported Saturday.
"Hi everyone, we wanted you all to know directly from us, that Shannon & I have decided to end our relationship as boyfriend & girlfriend ...," Hough said.
"However, we love and care about each other very much and will remain friends and in each other's lives," Elizabeth offered.
"Thank you everyone for all your sweet words & encouragement -- it really means a lot to me!" Elizabeth offered a few hours later.
E! Online said the "American Pie" actress met the "Dancing with the Stars" professional dancer when they were paired for the ABC program's sixth season.
The couple dated for more than a year before Friday's Twitter announcement.
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