Why, unlike Italy, monarchies have survived in some Northern European states?

In some Nordic countries, monarchies persist, but their rule is symbolic, representative. These are countries such as Norway, Sweden, Denmark, Belgium, the Netherlands. This also includes the UK. Monarchies survived because the members of the royal family themselves voluntarily relinquished power in favor of the further democratic development of their countries. That is why in the aforementioned countries, monarchs and their families are honored and respected.