Complex sentence: The pair does not have much money left, so her husband suggests that she buy roses to wear with it, but after Mathilde disagrees he suggests borrowing something from her friend, Madame Jeanne Forestier.
Split into simpler sentences: The pair does not have much money left, so her husband suggests that she buy roses to wear with it. After Mathilde disagrees he suggests borrowing something from her friend, Madame Jeanne Forestier.