Nice idea indeed!
To be honest at first sight it looked to me more like a bar scene or some kind of business talk. Maybe because of the expressions on the faces.. although they are very reduced, to me both characters seem a bit "cheecky" and up for no good somehow ;) So I would not make the connection to the topic at the moment to be honest.
will try to refine the expression...
Great concept and representation! Would it be maybe interesting to continue the idea with more graphics maybe with the same characters and tell a whole story about sadness and its opposite?
hmm... let see if i can come out with something more graphical
Nice start !