Question Summary:
If a couple is not involved romantically, when will the nikāhbreak?

Question Detail:

1) If a couple is not involved romantically for a while, then will the marriage get broken automatically?  Is there any time constraints/limitations?
2) If a couple is separated (not divorced officially),is there any time limit for marriage to be nullified?

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
 
As-salāmu ‘alaykumwa-rahmatullāhwa-barakātuh.
If a husband takes an oath to not engage in marital relations with his wife for a period of four months or longer, then the couple will be divorced at the end of four months.  However, if the husband broke his oath and engaged in marital relations before four months, then the marriage will be valid, although the husband will be responsible for the kaffārahof breaking his oath, which is to feed ten poor people for two meals (morning and night) or to clothe them.  If he is financially unable to feed or clothe them, then he may fast for three consecutive days. 
On the other hand, if the husband did not take such an oath, rather the couple has simply decided to not engage in marital relations and/or live separately, then the couple will still remain married.  However, this is obviously indicative of a larger issue and, hence, the couple should seek marital counseling or mediation through a mutually respected individual, such as an elder in the family or the local imam.
And Allah knows best.
MuftiAbrar Mirza
Chicago, IL (USA)
 
Under the Supervision of Mufti Ebrahim Desai (South Africa)
 
لَا يُؤَاخِذُكُمُ اللَّهُ بِاللَّغْوِ فِي أَيْمَانِكُمْ وَلَكِنْ يُؤَاخِذُكُمْ بِمَا عَقَّدْتُمُ الْأَيْمَانَ فَكَفَّارَتُهُ إِطْعَامُ عَشَرَةِ مَسَاكِينَ مِنْ أَوْسَطِ مَا تُطْعِمُونَ أَهْلِيكُمْ أَوْ كِسْوَتُهُمْ أَوْ تَحْرِيرُ رَقَبَةٍ فَمَنْ لَمْ يَجِدْ فَصِيَامُ ثَلَاثَةِ أَيَّامٍ ذَلِكَ كَفَّارَةُ أَيْمَانِكُمْ إِذَا حَلَفْتُمْ وَاحْفَظُوا أَيْمَانَكُمْ كَذَلِكَ يُبَيِّنُ اللَّهُ لَكُمْ آيَاتِهِ لَعَلَّكُمْ تَشْكُرُونَ (المائدة: 89)

الإيلاء هو اليمين على ترك وطء المنكوحة أربعة أشهر فصاعدا
(المحيط البرهاني، كتاب الطلاق، الفصل الرابع والعشرون: 5/200؛ إدارة)

وحكم الإيلاء شيئان أحدهما يتعلق بالحنث بأن يقربها في مدة الإيلاء وهو لزوم الكفارة...والثاني يتعلق بالبر بأن لم يقربها حتى مضت مدة الإيلاء وهو وقوع تطليقة بائنة
(المرجع السابق)