Anything is possible. It all depends on whether or not the school will allow this. Many require a good reason for a LOA and usually travel doesn't count.
There is another concern, if your friend has borrowed money for school. While she is away from school her grace period will pass and she will be expected to make payments sometime during that year off. While the payments will stop when your friend becomes a student again, as soon as she graduates the payments are due again, immediately (there is only one grace period for a borrowed amount).