I thought women usually had problems mainly with their mother in  laws.
My problem is my retired father-in-law-to-be.  Father in law tends to buy a one-way ticket - often leaving his wife at home - the day before he travels and just informs us he's turning up. Leaving my partner and I to buy a return ticket - not by mutual consent mind you (my partner bleats that his father is "just trying to help" or "that's just the way he is" in response to my every objection) - but usually because I've had to nag for a week or two to get it, causing problems between the pair of us. This last time his father stayed for 6 weeks in total.  If I didn't nag or make things unpleasant he would almost certainly stay for 3-4 months at a time several times a year.
The guy isn't mean-spirited though, I'll grant him that.  Just rather strange, interfering and rude. He does strange things like excercising without a shirt on outside the kitchen window several times a day (a 75 year old man that I barely know...) and telling me that he wants to poison himself.  It, frankly, makes me rather uncomfortable.  Then there's the giving his opinion (or rather telling his son what to do) in every aspect of our lives.  Not only that but he's wanting to be in on decisions like what furniture we buy and I caught him putting a nail into the living room wall the other day to hang a picture he'd bought WITHOUT ASKING.  We don't have kids, but he's constantly commenting on the way I discipline our dog and I overheard him asking our cleaning lady whether she knew anyone who could take our cat the other day while she politely asked whether I was okay with this.  He insisted it was not a problem!  When I questioned my partner about whether this was acceptable behavoir, he simply said that his dad doesn't like us having a cat in the house, so thought he'd help by trying to get rid of it!?  By asking our cleaning lady?!?
This is not to mention his ridiculous misinformed and misjudged ideas.  He has said some pig-ignorant things about a disabled member of my family and is constantly making racist and homophobic comments and expecting me to back him up.  It makes me squirm to have to politely reply that I do not agree, when I want to say exactly what I think... OF HIM!!!
He's constantly referring to "our" home and what will "we" do about things that frankly don't concern him.  I feel as if I'm not just marrying my partner but also his parents!
To explain my particular frustration about this situation - I moved in with my partner several months ago after 3 years of living a long distance relationship.  We decided to do this after much discussion and because someone had to make the move since we're planning to get married soon. Moving in with just him was already stressful enough, as I am used to being massively independent and living on my own.   I had to give up a very good job and my appartment in order to do this.  I was aware that his parents were around alot and treat him like a little child and our house as their own (he is 40, I'm 31), my partner's father even greeted my parents the first time they met - who by the way had come to visit me - with "welcome to our home", much to my mother's bemusement. When I insisted that I would not move in with my partner if his (retired) parents carried on visiting as often or for as long periods he reassured me it would not be a problem, they were just there to help.  Since moving 5 months ago they, or at least one of them, have been here for 3 of those. When they're not here they get upset if they don't talk to me on the phone at least every other day, when I speak to my own parents every other week!
We have therefore had very little privacy since I moved in with him (me who cannot even stand the intrusion of having my own family visit for more than a weekend - which I was clear about).  We even get woken up by his father in the morning and my partner gets told off if he is late setting off for work!! As someone said, it is almost like his father is competing with me for his attention.
Since moving I have tried to talk to my partner about it and it is as if he doesn't want to hear. I am getting to the point where I'm going to call off the wedding if he doesn't do something about the situation.  I can't even imagine how bad things are likely to get if we have kids!!  I already feel like I'm being slowly suffocated.