The first division to come between them in many years occurs when Maxime announces that he is having an affair (and has hastily made plans to leave his wife). Matters are more complex than they seem because his new lover is their newest client, up-and-coming artiste Camille (Emmanuelle Beart). Stephane barely comments on the wisdom of mixing business with pleasure, although he does share some of his thoughts with old friend Helene (Elisabeth Bourgine). In no time at all Stephane is slaving over Camille's favourite instrument, tuning it for some upcoming rehearsals (and shadowed by Maxime, who has suddenly become obtrusive in the workshop). Maxime seems energised by his new relationship, discarding his old habits and gleefully doing anything in his power to please Camille.
In a series of chance encounters, Stephane and Camille bump into each other (usually in a professional capacity). However, when she drops by Stephane's bedroom (which adjoins the workshop) and starts unloading her troubles their relationship undergoes a shift. Stephane has the feeling that is she wasn't going out with Maxime then he would have had a chance (not that he's jealous of his associate). The question is whether he should pursue Camille further, with the ultimate aim of seducing her, and whether he wants to do this anyway. Strangely, Camille has been having similar thoughts, although she favours more direct action. That her mentor and protector Regine (Brigitte Catillon) disapproves of Stephane only intensifies her feelings, which has a fairly detrimental effect on her playing.
A film which approaches the subject of love in a decidedly adult fashion is unusual in itself, but one which embraces the contradictions inherent in Stephane is special. For he is the owner of the title organ, a man who typifies the characteristic of reticence. Outwardly he is an enigma, avoiding all emotional entanglements and reliance on others. Inwardly it's impossible to comment, since it's entirely plausible that even Stephane doesn't know why he acts in certain ways. Acting the martyr he claims not to have led Camille on, when she starts to react to his presence, yet this is entirely false - he just seems to be playing games. When Camille falls into obsession, as Stephane cuts off from her, his behaviour is atrociously cruel. Yet how can one feel anger for Stephane, since he somehow suffers the most of all - a victim of his own introversion.
In common with many European films Un Coeur en hiver centres on a small number of complex characters, each animated by performers who submerge themselves in their role. This is absolutely the case here except that the results are outstanding. Auteuil performs an exceptional balancing act, drawing Camille onto the brink of commitment then damning her, all without becoming demonized himself. Beart is equally convincing (especially in her faked musical abilities) as the tough yet vulnerable ingenue. Dussollier is good as the third corner but he never quite reaches the heights of Stephane and Camille. Coupled with an excellent selection of Ravel's compositions, Un Coeur en hiver is a movie which tears at your heart and finishes in a way entirely appropriate to the story - unfulfilled and incomplete.