He notices an odd pair of boots by the door.

Not his; his wife wouldn't be caught dead in 'em.

He relaxes when the inside tag reads

  "Women's: Size 8".

They disappear from house (and mind) within the day.

The boots would then reappear

  occasionally.

An internet search would reveal

a paramedic's standard shoe

was sitting by the door

  of an accountant and a bartender.