It is said one gets married for seven lifetimes. What might happen if only one person of the couple attains Moksha and the other doesn't during these seven lifetimes?
1 Answer
As per the Kāraṇāgama, the belief about husband and wife's togetherness for seven lifetimes might be construed null & void.
Chapter 2 (dvitīyaḥ paṭalaḥ), kriyāpādaḥ, Kāraṇāgama
महादेव उवाच:
सङ्कल्पाधिकृतिस्तासां नास्ति स्वगर्येषु कर्मसु । सिद्धा विमोक्षाधिकृतिर्न निरोद्धं हिशक्यते ॥ ६० ॥
Bhagvān Shiva said -
It is not right for a woman to do will for the deeds which are intended to reach Heaven but for the Salvation, right is ready for her. None can prevent so.
.......
पतिपत्नीत्वसम्बन्धो न नित्यः कल्पितो हि सः । नारीिनरत्वादिकमप्यैहजन्मिकमीरितम् ॥ ६२ ॥
Relation of wife and husband is not an ever-lasting—thing. That is the thing of supposition. It is said that to be a woman or man is also of this incarnation only.
नैव स्त्री न पुमानेष नैव चायं नपुंसकः । यद्यच्छरीमाधत्ते तेन तेन स लिप्यते ॥ ६३ ॥
This soul (Atma) is neither a woman, a man nor an impotent one. It wears that and that body in which and which it dwells.
नारीत्वमैहिकं वाऽपि भार्यात्वं कल्पितं तथा । निरुन्धतः कथं तन्व्याः पन्थानं मोक्षगामिनम् ॥ ६४ ॥
To be a woman is the subject of this incarnation. Like this, to be a wife is also. How can these items of the subject (womanhood, entity of wife) prevent the path of salvation for her?
English Translation by Shri R.M. Prabhulinga Shastri
To Conclude:
What might happen if only one person of the couple attains Moksha and the other doesn't during these seven lifetimes?
Purely basic to the above excerpt from the Kāraṇāgama, both the jivas residing in the husband and the wife's body are independent of each other in regards to attaining Moksha or Salvation.