Edited by Alaura5 - 3/3/13 at 4:32pm
My son had a hard time transitioning for a while. He is 26 months now and has adjusted. I remember that he would have meltdowns when he would return home (sometimes). We moved out when DS was 14 months (though we had broken up at 9 months) and it's been a year now with the shared custody. My son also goes to his dad's house to visit. I agree with always letting him know what is going on and keeping things as consistent as possible.
At one point it was really intense and DS would throw tantrums when he came home. I talked with my friend about it and she suggested meeting him where he was upon his return, so if he was wanting to play and be energetic, to engage with him in that way rather than the other way around (him adjusting to me). I did that once and it seemed to help and then shortly after that he stopped having the meltdowns. Now he comes home, goes in the fridge and quickly busies himself with play. So, I am confident this will pass. For me, the 1-2 age was very tough all around.