Is it obligatory to fulfill the vow of fasting the months of Rajab and Sha'ban every year, given the difficulty in doing so after marriage and the passage of 15 years since the vow was made?

Whoever vows to obey Allah the Almighty, let him obey Him, and it is not permissible to deviate from fulfilling the vow, for a vow is a grave matter. Marriage does not prevent one from observing obligatory fasts or fasts vowed, and it is not permissible to abandon a vow except for one who is unable to fulfill it due to a chronic illness. If a person becomes unable, it is permissible for him to offer expiation for it.