Thanks!  I do make a big deal about leaving.  I snuggle him and kiss him and tell him I love him and all that.
 
I'll start going outside for a minute or two at a time during the day and then come back, taking the keys with me.  Maybe if he keeps seeing that I'm going to always come back, he won't be upset.  Normally, he goes outside with me all the time.  That's good advice!

   Thanks again!!