I hope this joke makes you smile! Have a good day!
Why do these kinds of stories always make us laugh?

The reason this joke works so well isn’t just because of the punchline. It’s because it speaks to situations that many people recognize. The beginning resembles a romantic or very polite story, then the ending brings everything back down to everyday reality.
Humor often relies on this contrast between what we imagine and what actually happens. And in a couple’s life, this contrast often exists: at the beginning, we want to be perfect, attentive, irreproachable, then normal life takes over.