My wife has had the exact same coffee order for years, and I know it perfectly. But every few weeks I ask her again. She rolls her eyes, gives me a dramatic lecture about how I never remember anything, and then carefully explains the order.
The reason I do it is stupidly simple: she gets animated over tiny things, and I like listening to her. I remember her coffee, her shoe size, the name of her childhood teacher, and which side of the bed she prefers. She thinks I'm forgetful. I'm probably going to let her keep thinking that.