Is the wife entitled to refrain from spending on her family to enable her husband to save money to perform the Hajj, especially since his salary is not enough to cover basic living expenses?

A husband must spend on his wife and children. It is not permissible for him to fall short in providing the obligatory sustenance for the sake of Hajj. Rather, he should save from what is surplus to the obligatory sustenance. His obligation to provide sustenance does not cease if his wife has a salary; her salary is her property, and she may dispose of it as she wishes. Her contribution to expenses is a help and an act of kindness. The husband is not obliged to save until Hajj becomes incumbent upon him, because Hajj is an obligation conditioned upon ability (istita’ah), and one is not required to acquire the ability in order to fulfill the obligation.