Well, assuming you have a "boy" in your life, I'm sure he does have to go through it if you're experiencing it when you're together. There's no way for a woman to have PMS and not affect all those around her.
But I'm sure you mean, why do they not have to endure the physical symptoms that we do. The answer is simple biology. PMS is related to hormonal imbalances that accompany menstruation. Boys don't have ovaries, huge amounts of estrogen and other biological and physiological elements that women have, which conspire to cause our PMS symptoms. These are all the things which make us uniquely female and make it possible for us to have the things we do appreciate such as fuller breasts, curvaceous hips, soft skin, and the ability to have babies. PMS is the price some women pay for the right to be uniquely feminine. It is unfortunate, but completely worth it.