Why are some mother-in-laws controlling and always looking for negative things to say about their son's wife?

Because they are bitter old bitches who feel they are owed something back for the time spent raising their boy.

At least that’s what my Mom told me.

love ya ma

Because the son is still tied to his mom’s skirt tail. He needs to man up and tell the mother (respectfully), if she can’t appreciate his wife than she should get out of their life.

Because some people are just like that.

I don’t think it is boredom at all.

They are not all that way. When I was with my ex, by the end of our relationship, I liked her mom more than her.

It happens. A simple clash of personalities between mother in law and any child in law as a matter of fact. But really, it’s what @Blondesjon and @AmWiser said. Those could be the most rampant reasons.

But of course, let’s not be naive not to think that sometimes it’s the parents in law who are probably in the right and their child is married to a mean and nasty nincompoop.

I think that the relationship between mother of a son and the woman that he chooses can be one of the most difficult of all relationships. A mother has been taking care of her son for a good share of his life, and then she has to step back and keep her mouth shut while he gets on with his life.
This is the way it is supposed to be, this is what we are supposed to be raising our children to do.
It doesn’t always happen that way.
Mothers who can’t stay out of their grown sons’ business aren’t always bitches, they just seem that way.
Some are bitter old bitches and deserve the nasty mother in law reputation.
Some are a bit lost without the role of mother/caregiver/nurturer that they have been living all their life.
I have three sons. My oldest is engaged. I plan to smile, be supportive, and keep my mouth shut. I like his fiance, but even if I didn’t, I would try to never let either of them know it.

What about the mother in law in the case of a son who is gay? I honestly think that this relationship (with a man instead of a woman) would often be easier on both of them. There isn’t another woman taking “her” place as the number one woman in his life.

I have had two mother in laws, I didn’t always like them, but I did try hard to get along with them, and I do believe that they tried hard with me as well.

My MIL isn’t exactly a bitch, but she is a passive-aggressive, manipulative pain in my ass. I could give you ten good reasons why our relationship is so difficult, but I think it comes down to this: I am her competition.

She never developed a life outside of her husband and two sons. Her boys were a large part of her identity. This is the woman who really was “so & so’s mom” instead of “Her Name Here.”

Her older son was still in college, on her dime, and living at home during breaks when her youngest married me. I was the one who upset the apple cart and stole half of her identity.

Why do I think she look for the negative? Pointing out what I do wrong is the best way to silently call attention to how well she did it herself.

They just want the best for their daughters. And since all the life was centered around the kids it’s not simple to just let them go and move on. Mothers in laws who constantly nag do not know anything better. [or they had the same problems coming from their m.i.l.s when they were younger]

Sometimes it’s the DIL that is the problem. I have had four DIL’s from my two sons and I got along beautifully with all but the current wife of my youngest son. She is the DIL from (expletive deleted).

In fact, I am still very close to one DIL, even though she has been divorced from my oldest son for 20 years – the mother of my three adult grandsons.

I was very close to all three of my MILs as well.

She’s just jelly… get her laid and she’ll shut up. Either that, or chloroform.

There can be a million reasons. I know that I continue to hope my son will find himself a good wife. I really wish he would get married. That said, it doesn’t mean that any woman will do. I think he deserves a good person. I don’t care how she looks, or how smart she is, but I do hope she is very loving, sensible, and honest person who wants a family with my son. The last part is something I know he has wanted for years now. Would be nice if she is funny too. But I wouldn’t have to live with her so funny isn’t that important to me.
Him loving her doesn’t mean we would be compatible so it doesn’t guarantee I will like her as a person. If I feel she isn’t being honest with him about her feelings and is simply using him than I will not like her. I mean, why should anyone like someone who is decietful. Love can make some people blind but it doesn’t mean that others would be blind to the reality.
In my case, if she isn’t someone I like, I will do my best to play it cool and be there to help pick up the pieces when things go wrong. I’m sure it won’t always be easy. But I’ll give it a try.

I had a rough start with my mother in law and I would say that in her case she was and still is possessive. However, she has come to realize how much I love her son and only wish to do right by him and she has come to like me. It only took like 15 years but she has eventually come to care for me like a daughter.
My husband wanted to write her off a few times but I told him no matter how wrong she was about me, she was always going to be his mother and always love him. He should never forget all the love and care she gave him through the years. I told him he would regret cutting her off someday if he did. So I would make him call her once in a while to keep in touch and keep their relationship alive. Now he has a really good relationship with her and when she passes on, he will have no regrets.

Well my MIL is the MIL from hell but I mostly just feel sorry for her now. She tries to control everyone around her and nobody appreciates it. Her biggest problem is rooted in the fact that she has yet to realize (at 73) that the only person she truly controls is herself. She has a laundry list of past perceived transgressions that go back all the way to 1962.

She hasn’t liked any of the daughter-in-laws, me most of all because when she jumps all over my boundaries I tell her back away. I do so respectfully. I’m also the only DIL to stick around for any length of time.

She is bitter. It is sad to see because she has a lot of things in her life that should bring her joy but she can rarely see that.

I agree with you, OP. Part of it is boredom. The MIL might have failed to develop any interests outside of raising children, and so when the children no longer depend on her, she is lost. As others have pointed out, she may also resent that she’s no longer the number one woman in her son’s life. Although I never really understood this, because shouldn’t she already be #1 in her spouse/partner’s life and be contented with that?