May I assume that Diesel is a rather young animal ?
Yorkies can be rather possessive and protective, right from the start. Your "play time" with him, reinforces the bond you have, and I'm not saying not to do that, however...
When you separate from him, it's like your abandoning him, and he wants to keep an eye on you, to keep you safe. This is a strong representation of the Pack Mentality which all Yorkies are bread to possess.
I suggest that you move his crate to a near location
in your bedroom. Possibly on the night table next to your bed, where he can see you. I do this with all my new Pups, where when they get lonely, all I have to do is stick a finger in the Crate where they can touch me, and they settle down quickly. This is a very basic need for them, you should support it.
Let him be your Protector.
PS:
HA, Marhcarter and I were writing the same basic response at the same time. Like Minds !
