The husband's anxiety stems from his health concerns and military background. It's understandable he wants to be on time. The wife's refusal to accommodate his anxiety, even slightly, seems a bit insensitive. A little compromise could ease his stress significantly.
The husband's demand is unreasonable and controlling. Insisting on arriving 45 minutes early for a simple X-ray appointment is excessive and disregards the wife's time and comfort. His 'military background' is a flimsy excuse for imposing his anxiety on his partner. This is a clear attempt to exert unnecessary control.
While the husband's anxiety regarding appointments is understandable given his health issues and background, demanding to arrive 45 minutes early is excessive. The wife's refusal to comply fully is reasonable, as her suggested compromise still allows for punctuality. However, some empathy towards the husband's anxiety would be beneficial. Therefore, while the husband is more at fault for his unreasonable demands, the wife could have shown more understanding.