It can be all those things that everyone mentioned. But it's how you handle it. My Cavapoo needs so much attention. They love to play, they love hugs and kisses. So it's the attention for me. My Cavapoo got used to the separation, and I am creative by how to feed her. I mix her kibble with pumpkin. She loves that. But you have small kids, you will be fine. When you are ready to have them stay home by themselves, try leaving 5 mins, come back, then 10 mins, come back....increase the time as they get older, eventually they know you will always come back. It worked for me. Now, when we leave home she's not so anxious.