Near the very end of the film, as they are leaving to return home, she utters the few words that tell everything.. 'I love you.' So there's little to doubt, she married the one close friend, but is seriously attracted to, and in love with the other (don't doubt it, the way in which it was whispered close to his ear can only mean one thing). Then soon after she has him pull over to the side of the road, and doesn't know (or is afraid) of what to say to him (and to herself). Many have had people they've known, and but for circumstances, would have gone with if things could have been different. Life moves on in all cases, and we don't always have the control we'd like of what happens to us. It's a good little film, and the cast is excellent. Not slated to win awards, but as a slice of life-relationships it's very real and enjoyable viewing.
