The Unexpected Guest

A seasoned yachtsman and an old friend of Meredith's, Geoffrey Stout, introduces Meredith to a girl he plans to marry within the month. The girl, Kait, is exceptionally friendly to Meredith and shocks the boater. Kait and Meredith  are forced to sit uncomfortably close, and she senses that Kait is sending out some obviously confusing signals. Meredith, having been out on the lake in the hot sun all day decides it's time for her to get home and take shower and get to bed.
She bids her sailing buddies goodnight and proceeds to the valet to get her car. Once she is ready to get underway she is given another shock by Kait as she jumps into Meredith's car and asks to go home with her. Getting home, Meredith decides to get to the bottom of the peculiar behavior of Kait, the would betrothed before her good friend Geoffrey gets the idea something deceitful is going on. When she confronts Kait, she confronts that she is only with Geoffrey so she could meet Meredith.
So now what is Meredith to do?