I would like to help you with your question.
You pose a very interesting question.
If you were a compulsive liar you likely would be lying about many aspects of your life..not just shopping.
Do you think you are afraid of your partner's response to your spending? Have you fought about money before? Or about your buying things?
Saying you found things doesn't seem believable. So...do you think he even believes you?
I see you are offline. When you come online I will be notified and then we can chat more.