Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) was asked about a man who stayed away from his wife for a month or two months and did not have intercourse with her; was there any sin on him or not? Could the husband be asked to do that? 

He replied:

The husband is obliged to have intercourse with his wife on a reasonable basis, which is one of the most important rights that she has over him; it is more important than feeding her. It was said that what is obligatory with regard to intercourse is once every four months, or according to her need and his ability, just as he should feed her according to her need and his ability. And the latter is the more correct opinion.

Majmoo‘ al-Fataawa, 32/271