He may sense your sadness a little in addition to things being different... it will get better soon.
My Sammy is pretty much happy anywhere, in any situation
Loki, however, does not like change in any way. He loves visiting my parents but after he's hugged everyone, he whines to leave and go back home to take a nap. He doesn't like anything that upsets his routine. But even being so nervous, he does adjust to new routines fairly quickly. When we take them to visit my brother he settles in fine after a day or so, especially if we bring all of his "stuff" like his crate, blankets (I make sure NOT to wash them), etc. Once he realizes we are staying a while, he settles in. My brother does little things for them, like buys them new toys, and the guest bed there is really low so they can jump on it without help, so they have a lot of fun with that.
My mom lets them jump on all the beds in her house too...they like beds...
Can you get him a new toy or something to distract him? And just spend extra time with him. If he likes your parents, have them spend extra time with him too.
He just needs to pick up from you that you are staying there now and that everything is OK. I notice a distinct difference in the attitude of my two when they know we are on vacation (with all of their stuff) and staying a while, and when we are just visiting for an hour or two. They do know the difference and they actually seem to prefer when we are staying, otherwise they act like "will you hurry up so we can just go home?" So just pretend you are on vacation
I'm sure that is what will happen, especially once you get settled into a new routine. Oh and just make sure he is tired. If my two are tired enough they will fall asleep anywhere