The love between Marius and Cosette blossoms like flowers in spring. He visits her every evening. Unknown to the young couple, Thénardier and his gang are lurking outside the house. When they plan to attack the house, Eponine intervenes and threatens to alert the police. She insists that she is not scared of her father, who relents and skulks away. Cosette and Marius's dreamlike happiness is broken when Valjean announces that he plans to go to England with Cosette. Marius is jolted back to reality "with a vengeance" (736).

Marius believes that the only way to remain with the woman he loves is to marry her. Despite their differences, he visits his grandfather to beg for permission to marry Cosette. Monsieur Gillenormand is willing to listen to his grandson, but his pride leads him to treat Marius coldly. They talk, neither able to truly state his affection for the other. Maris finally asks for his grandfather's permission to marry Cosette. However, Monsieur Gillenormand is not convinced by Marius's plan. He suggests that Marius should make Cosette his mistress, rather than his wife. This infuriates Marius. He criticizes his grandfather for the insult to Cosette and leaves.