Eventually the person gives up normal activities. They don't go fishing. They don't go camping. They quit school or get fired. Sexual activity decreases.
Recreational activity decreases.
Time with the children decreases. Any activity can go but the drug stays and grows more and more important. There are social consequences caused by the drug use. Problems with the spouse, the law, at school, with friends, with parents, the problems mount but the chemically dependent person keeps dealing with the problems in the same way. They get relief, the only way they know how, with their drug of choice.