In 2 Nephi 28:8, it talks about how many people believe that they can get away with little sins, and then be "beaten with a few stripes", and be saved. This is false. If such a philosophy is embraced, sooner or later those little sins will seem no fun anymore, and they'll turn into bigger ones, and then bigger, and bigger still. If someone goes and destroys their lives, the fact that they were sealed to their parents doesn't guarantee them anything after this life.