His mum

The first woman in any man's life is always his mum, and she'll always be there. It doesn't matter whether you think you know her well or you've only met a couple of times: you need to take her seriously! The potential monster-in-law can be as cunning as a fox and can make your life hell...  

The monster 
She could be completely harmless...or she could take an instant dislike to you and do everything she can to scupper your budding relationship. Some mothers have an amazing ability to hate you with a passion right from the start, even if they don't know the first thing about you. You can't do anything right, however hard you try, and you're never going to be good enough for her precious little boy. This kind of mother will go out of her way to 'bring him to his senses' and split you up.

A well-known scenario: she's downright nasty to you, you get angry and tell him exactly what you think of her, and you start rowing as soon as she's out of the room. He feels feel torn between the two women in his life and doesn't know what to do: he can't choose between the two of you. You then get frustrated because he's not standing up for you against his monstrous matriarch. The result: more rows. And when it all ends in tears, you know she's got exactly what she wants... 

The mother hen 
At first she's all sweetness and light: she's a model housewife, she cooks, cleans, worries about anyone and everyone, and she seems to like you. But when she starts taking over, alarm bells start ringing in your head. Example: you and Romeo are planning a summer holiday in the Maldives, but as soon as you mention it to her, she tells him there's no way he can go because they're planning a big family holiday in the country. She'll become more and more controlling, and he won't understand why you feel she's invading your territory, which is only natural - he's put up with her all his life, after all. He'll think you're ungrateful for all her well-meaning interference, and it can drive a wedge between you.  
 
The NBF 
If there ever was an 'ideal' potential mother-in-law, you'd be forgiven for thinking she's your new best friend - at first. You hit it off right from the start, you pop in for cups of tea when he's not there, you go shopping together and she even gives you advice on what he likes (from his favourite meal to choosing sexy underwear). 

But all is not what it seems. There are rare diamonds out there who will treat you like their own daughter, but unless she really is one of these, there are certain lines you shouldn't cross with a potential mother-in-law. It's not her business to tell you what he likes and what he doesn't like! Maybe, subconsciously, she's trying to compete with you for his time and affection. Either way, it's never going to be good for your relationship.