In his youth, he vacationed differently. Everywhere he went was a place he could live, a potential future life. He could live here, he’d tell himself. Or he could meet a woman there, and start a family there, and become a citizen of that place. Mexico, Hong Kong, France, Italy, Western Indiana, etc.
Eventually, he met a woman and chose a place – the best woman and the best place – and his future was fixed. The world was good, but the world was no longer full of all these possibilities. What, then, fills the void where possibility once lived?
Much of middle age (and beyond) is a struggle to find meaning in the face of the realization of the finiteness of your remaining days. I think that, by and large, I'm doing a fair job at that, but I still struggle a bit with travel, for the very reason above. I used to imagine myself living in whatever place I visited, and those imaginings were plausibly something more than fantasy.
Now, not so much. It would be a huge undertaking for my wife and me to uproot our lives and move to someplace exotic and different, but even if we were to do so, we couldn't move to everywhere exotic and different. And anyway, we wouldn't be "starting a new life" there in the same way that a young person would.