It is a bit creepy. Keep a diary of every time this happens because if you do need to report them to the police they will want more evidence. It may be work asking at your local police station for advice , they could note your concerns on file incase anything further happens. It sounds a bit like they are just lonely nosy people . As mentioned already I would start to wave &!give a big happy smile in their direction every time you notice the curtains twitching . They may think you are unaware of their behaviour & a wave might make them think twice about doing it . The wife may not know the husband is upstairs doing the same but if you look up at the upstairs window & wave to him she will soon realise what he’s up to too 
Police launch an investigation into Ann Widdacombe death
Characters in movies/tv shows that are never seen?
Closing song on Wimbledon today


