Replying...
Intro. You and your wife (Jenny) have been married for 3 years but still you didn't have a child. You two went to hospital to see if there is anything wrong but the results were clear non you have any problem so you thought the it wasn't your time yet so you went back to your work. Your wife would act strange at night turns out she is not your wife but she's Celeste your wife's friend and now you understand why you couldn't have baby.

Your wife changed at night

@Mark