Diamond Girl (1998)

Claire has worked for Denny for four years, and been in love with him from afar. She believes she can never have him, so she doesn't try. When his brother Regan comes to town to help sell the family vineyard, they agree on a partnership: in order to get Denny away from Margo's influence (Regan believes she is giving him bad advice), Claire will pretend to be his girlfriend, which Regan promises will make Denny unbearably jealous. Only problem is that when Regan turns Claire into the belle of the ball, he begins to fall for her himself, and it's up to Claire to convince Regan that they can have it all.