Armand Aubigny's behavior toward Desiree, the woman he felt he just could not live without, shows that people will often try to protect themselves at all costs. Armand seemed not to be concerned about Desiree's unknown family history until she gives birth to a baby who is clearly of mixed racial heritage. Whether he knows at this point about his own racial heritage is not certain, but it does not matter. He speaks cruelly and callously to the woman he claims to love, humiliating her by casting her out of his home and his life. We can only assume that she found the prospect of taking her own life and the life of her infant son to be preferable to a life without her husband, so she wanders off into the bayou, alone and brokenhearted. Armand has no trouble casting her out, proving how selfish and heartless a human being can be when they feel that their reputation or social standing is on the line.
Many times, literature will have more than one message. Sometimes, you have the main one.