There isn't much you can do, chi's are so people oriented they are going to be upset and unhappy when their special human leaves. Favorite toys and a cuddly spot with a blankie or something that smells like you will help
I always give Bella some extra attention about 1/2 hour before I leave, then when I am ready to go I turn on the radio and just leave. I don't say anything to her . I have already made sure she has food water etc. Sometimes when we talk to them and try to assure them we will be " right back " our voices only tend to cause them to feel apprehensive. I also speak briefly to her upon my return, but I don't pick her up right away.......then after a few minutes, we have a massive kissing session LOL! All of this is hard to do, but it best for her in the long run. Works for us.