Is there a minimal amount of time which a husband must have marital relations? What if the husband does very infrequently and the wife does not complain?
Most choson and kallah teachers teach twice a week. The important thing is that there should be harmony and no ill feelings between the couple. If the wife does not complain does not always mean that she full heartily agrees. The issue should be spoken out explicitly and the husband should explain his position.
O:CH 240:1 Biur Halacha ד”ה ת”ח, E:H 76 Pischey Teshuvah 3