He does laugh quite loudly, and show lots of teeth, so don't know if she's confused and thinks he's angry or upset. As he is SAHD, it can be quite wearing for him, esp as she sometimes takes ages (anything up to an hour) to calm down again.
Any ideas of how to reassure her? Or do we just wait for it to pass?
(She doesn't mind if I laugh, in fact she smiles at me)