Possible separation anxiety?

Since I became unemployed last summer, I have been spending most of my time here at home with the cats. My husband recently brought it to my attention that one of my cats is freaking out when I do leave. I went to the store the other day and he said Willie was running around howling, looking out the windows, and pawing at the door. My kids said they've seen it too. I really don't know what I can do about this. I have nowhere to go and limited funds to go anywhere on so I spend about 95% of my time here. I will eventually find another job and I don't want him to be freaked out when I do have to be away from home every day. Has anyone else gone through this or have any suggestions on helping him not become so dependent on me being here? The other cats don't seem to have an issue with it. If it helps, Willie has some Maine Coon heritage and is 2 years old.