CK writes:
Let's take a simple example - when my significant other says she is going off to work - how do I know she is? she could be off meeting another boyfriend?
The analogy doesn't hold, CK. Even if you don't know where your girlfriend is, you CAN find out empirically. You can follow her and see where she goes. You can even take someone with you to confirm what you see. There's your evidence.
When it comes to the existence of God, however, no such option is open to you.
You are equating a lack of evidence with the ability to get it. When we say "lack of evidence" we mean that there is NO means of empirical confirmation.