I'm assuming Aiden did all of that running around to get the perfect glass because of his guilt (and it also got him out of the house bec he couldn't face Carrie). Had he not slept with Kathy, he may well have told Carrie to get over it and that they'll find something.
I think Carrie was justified in being angry about the glass. I mean, what kind of muppet chucks a rock at a glass window, esp in that type of historic house?
And I guess Aiden meeting Duncan and then leaving his script on the table is his man-baby way of ending the relationship. After what Carrie said, he probably put 2 and 2 together and got 5. So he sulked off back home without even a conversation. A muppet and a coward. Hope that's the end of him.