If you're a young playwright then we have much to look forward to in the future.
I thought this was a great little piece.
Suggestions: (And I mean suggestions!):
I would place Gordon and Carrie, one each side of the stage, leaving the centre stage for the interaction between Mary and James. Each time either Gordon or Carrie speaks, they are lit, otherwise they are in darkness.
The argument:
After the argument, Gordon speaks of the cases of 'unrequited love' and how people react to it. The main stream seems to be that people just do not have the courage to actually tell the object of their desire how they feel. Therefore, and this is very much up to you, perhaps you could write the argument in such a way that both Mary and James are each brought to the brink of giving the other the opportunity to express their real feelings, but don't.
We as the audience will then see that moment of opportunity pass and then realize exactly what Gordon and Carrie are saying.
Not sure even I understand what I have written here (!) but I hope it helps.
Once again I think this is a great piece and you should be proud of it.
