Is it permissible for one spouse to travel alone to another country for a summer vacation?

There is no harm in a wife traveling for leisure, provided two conditions are met: the husband's permission and the presence of a mahram, and that the travel itself is permissible according to Sharia. Travel to non-Muslim countries often involves Sharia-related caveats and temptations, along with the expenditure of considerable sums of money and the waste of time on matters difficult to justify Islamically. Furthermore, tourist destinations are frequently filled with forbidden acts (munkarat). A person's travel to a place where there is munkar that they cannot change, or where they fear falling into sin, is forbidden unless there is a dire necessity. The Muslim is accountable before Allah for their time, their wealth, and their body.