What is incumbent upon a wife who vowed to perform Hajj because her marriage was completed, but she does not have the ability to fulfill it?

A vow to perform Hajj is considered a vow of obedience that must be fulfilled as long as it is a legitimate act of worship. If the wife has not yet performed Hajj al-Islam, she should prioritize that first, and then perform the Hajj of the vow. If she is unable to perform Hajj, she should wait until she can. Alternatively, she can appoint someone to perform Hajj on her behalf if she has the financial means for Hajj but her inability is not expected to cease. However, if she is neither able to perform Hajj herself nor possesses the means for someone to perform it on her behalf, then she must offer an expiation for breaking an oath (kaffarat yameen).