Quote 7
She had no dowry, no expectations, no means of being known, understood, loved, married by a man rich and distinguished; and she let them make a match for her with a little clerk in the Department of Education. (1)
Mathilde's future prospects are not in her own hands. She's a woman, which means the quality of her life will basically depend upon her family and her husband. And in both respects, she's out of luck, as far as she's concerned. With so much powerlessness, it's no wonder she's frustrated and dissatisfied.
Quote 8
She had no dresses, no jewelry, nothing. And she loved nothing else; she felt herself made for that only. She would so much have liked to please, to be envied, to be seductive and sought after. (5)
Mathilde wants to be desired by men. To some extent, even her desire for wealth is just derivative of that. Her highest wish is to be approved of and wanted by someone else.
Quote 9
But by a violent effort she had conquered her trouble, and she replied in a calm voice as she wiped her damp cheeks... (20)
Mathilde comes across as overly sensitive and emotional. She has to work very hard to control her emotions. There's a feminine stereotype for you on which Maupassant is playing.