If Scarlett Johansson, Angelina Jolie or Jessica Alba started sniffing round your other half you'd obviously have trouble keeping him on the straight and narrow, but they're not the ones you want to watch. He may well fantasise about Scarlett, but he knows full well it's never going to happen. 

The women in your own circles are the ones you want to keep your beady eye on: they're far more likely to cause problems between you and your other half, and you're less likely to suspect them of trying to scupper your relationship. 

Even if they're all sweetness and light on the surface, the women in his life (and yours) could have it in for you, so you need to be on your guard! 

Here's our guide to handling the mother, the ex, the best friend, the work colleague and - yes - your best friend.