Forget Me Not (2009) on Netflix

Plot summary

Sandy Channing is the class president at her small-town high school, and graduation weekend has arrived. She and her brother Eli are bound for college. The celebrating starts at a party at their friend T.J.'s house, and the group then heads to the graveyard to play a ghost version of tag. A girl their age, a stranger to them, joins in and wins. She asks Sandy whether she remembers her, and Sandy does not. The girl answers that she will, then leaps from a cliff, and a police search finds no body. T.J. has bought an engagement ring for his girlfriend Lex Mitchell, whose brother Jake is Sandy's boyfriend.