As Anne goes out for a ride on horseback, she encounters a strange woman rider who shrieks at her, and she rides away in terror. When she returns, she is comforted by her mother and father and fiancee. But then they are interrupted by David, who she broke up with previously, who wants to get back together with her, and she frets that she is indeed choosing the wrong path.
Then we see a simlar tableau, only now Anne is older and dressed in black and we realize that we are seeing the other rider. As it turns out, this is Anne if she makes the wrong choice, if she chooses the wrong man to marry and has 25 years of heartache. Only now does she realize that it was herself that she saw that day so long ago. Then we see her husband as he rounds the corner. It is not her current fiancee, but David, who interrupted the events of that day, and we are returned to the present.
And at that point he calls to Anne as she stands on the porch and they run away together, presumably into a future where she becomes the lady in black and a number of years of anguish, where she will again return to her past self and try and warn the younger version of what she will become, only to fail again and again and again.
