It is the baby's first growth spurt. Major growth spurts occur at 2, 3, and 6 weeks, 3 months, and 6 months. They can last a little more than week (such as in your case). If a two week old baby is demanding the boob, it probably needs it.
However, there are babies who have trouble nursing and will keep on wanting the boob in attempt to get milk out. It IS possible that your baby has has a tongue-tie, which is making it difficult for him to get enough milk. Is your baby gaining enough weight? Does he/she have enough wet diapers?
If it is just the baby needing a lot of breast feeding, and your wife is unable to manage the four year old and the newborn (quite a challenge, really), she can try pumping. It can be a little less strenuous, especially when you will be there to help in the evenings.
There really isn't a way to alter a two week old baby's eating habits - it's not a habit, it's a need.