International shipping can take a long time depending on the service you used and the country you're shipping to. For all services, the United States Postal Service® hands the package off to the destination country's postal service at the border, and once they do it's entirely out of their hands. Although some services are faster than others, they all depend on the foreign postal service prioritizing the package within the country.
Not all countries have as good of a postal service as the United States, so some do not support end-to-end tracking. It’s common to see a package’s tracking status stop updating once it has left the USA, even though it’s still on its way.
Shipping internationally can also take a long time not only because of the distance involved and the amount of times the packages changes hands, but because your package might get caught in the destination country’s customs, where it's analyzed for whether the recipient owes taxes or duties for importing it. Customs is a country-specific issue, with every country having different laws and taxes, and unfortunately there's no way around it with international shipping,
Because of the long delivery times and potential for taxes to be owed by the recipient, it's really important to set expectations on your website for international orders.