It is commonly stated that the events of Megillat Ruth take place around Shavuot. However, this is not quite accurate.
"...And they came to Bethlehem at the beginning of the barley harvest" (1:22) - the first barley harvest occurs at Pesach, not Shavuot, as show by the Omer sacrifice.
"And [Ruth] stuck with Boaz' maidens to glean until the end of barley harvest and wheat harvest; and she dwelt with her mother-in-law. And Naomi her mother-in-law said to her: '... And now Boaz our kinsman... he is winnowing the barley in the threshing-floor tonight." (2:23-3:2)
So in short: Ruth left Moav around Pesach, and she got married around Shavuot.
Both parts of this are parallel to the earlier experience of the Jewish people: leaving Egypt on Pesach, and receiving the Torah (described by Chazal as a marriage) at Shavuot.