I always get sad when I come home from a great trip, but I get busy planning the next one. The worst I had was coming back from an extended hike on the Appalachian Trail. I felt out of place in the world, didn't talk to friends just moped around. The worst was getting up at night to use the bathroom, it took me forever to find it since I thought I was still in the woods. I recall my spouse turning in the light asking me wtf I was doing, I was standing in the closet ready to pee. Took 3-4 days to snap out of it and not be exhausted from a grueling personal challenge. Get on to planning your next adventure and be grateful you have the ability to travel. It's a beautiful thing!