Grandpa died, mainly because your father was filial. In ancient times, he was filial for three years. Of course, in modern times, it is no longer necessary to be so strict. As a grandson, you don't have to stick to these old customs. Even according to the old rules, before going to an important memorial service, you only need to fast for three days, live separately from your girlfriend, and take a shower and change clothes on the day of the memorial service. The old man attaches great importance to the first seven days of his death.

China people's funeral custom is based on the time of the deceased's death and the date and hour calculated by heavenly stems and earthly branches. But people are used to thinking that "the first seven" refers to the seventh day after death.

Extended data:

Customs taboos vary from place to place, and the usual taboos for the death of Han elderly people are roughly as follows:

1, a month without shaving;

Don't wear bright clothes and don't visit (into other people's homes) during the seven-day funeral.

Don't take a bath before the funeral.

Don't take part in "happy events" during the mourning period. In ancient times, the mourning period was one to three years, but now it generally means seven days.