Also nasty business when three people love each other, but not in reciprocal ways. Example: Guy A lusts after Girl B, who lies awake at night fantasizing about Guy C, who in turn wishes that Guy A would notice him.
A menage a trois seems to be a ludicrous way to resolve this, as quasi-suggested in Chasing Amy, but no more so than any other alternative resolutions to this decidedly squeamish situation.