The central theme of "Two Little Soldiers" is the incompatibility of friendship and romantic love. Jean and Luc are best friends under the most trying of circumstances. When both fall in love with the same girl, however, that friendship cannot survive, and it ends in tragic circumstances.
Jean and Luc are comrades in the military, and despite their shared involvement in a system that traditionally allows "little freedom and little dignity for individuals," they are the best of friends. Every Sunday, the two make it a point to share a meal and some time for relaxation out in the countryside. Their idyllic relationship is challenged, however, when they meet a girl in whom they are both interested. Although neither directly declares his feelings towards the girl with the other, deception enters into their friendship as Luc begins to actively court her, unbeknownst to Jean. Luc even borrows money from Jean, who, not knowing what he is using it for, willingly lends it. When it becomes apparent to Jean that the girl is enamored of Luc, he suddenly realizes what has happened. His hurt is so great that he commits suicide, throwing himself into the river.
The betrayal felt by Jean is especially devastating because he not only has lost the girl that he loves, but he has also lost a friendship which he had valued greatly. Although Luc may not have known the true extent of his friend's feeling for the girl he is courting, the fact that he pursues her secretly indicates that he must have sensed that his actions would hurt him and create a rift between them. The bond of friendship had to have been violated for romantic love to bloom in this situation. The conflict between the two entities is so great that it is impossible that both - friendship and love - would have been able to survive in conjunction with each other.