I second what elliemay said - the therapist really does always come back. It only took me two years of vacations to finally accept that!
Like ECHOES said, I try to schedule something else for the time I usually see T, something that I enjoy. This last time T was away was really hard, so I wrote T a letter each day, which was surprisingly quite helpful. I plan to try that again during Ts next break in a few months and see if it is as helpful then.