That's a shame/pity

Boy: I recommend you buy X product.
Girl: Okay, I'll try that.
Later on...
Boy: I'm afraid it's out of stock.
Girl: That's a shame.

Is it being impolite or insensitive to say 'That's a shame/pity' in the above scenario especially if the person giving the recommendation is excited, but later on realises it's out of stock? I wonder if saying such remark embarrasses that person and therefore should be avoided. If so, what remarks do you suggest are more emphatic/polite for sharing someone's disappointment?

Sorry, I asked because I'm a non-native speaker. Thanks in advance for your input.