I know what you mean, T&P Mom. Once we had to leave our cat alone in our apartment for about 10 days to go to Romania to the seaside (it's just too complicated to take them across the border). Of course, I had a friend from work to take care of him, at least once in two days (but he was not a cat lover and... you can imagine... Anyway, he was my last chance).
When we came home with my sister and opened the door, he turned and just walked away. He wouldn't even look to us for more than one hour. But after more than one hour he showed us how much he missed us.
Never did that again. We always ask someone to live in our apartment for the period we're gone away.