To feel upset me and DS have lost friends and it wasn't our fault

The thing is, she believes her child and you believe yours. Although you report what was apparently said as fact you only have your child's word for it. That said, this kind of fall-out is incredibly common between children. You perhaps invested more in the adults' friendship than the other couple did. Try and take this as an opportunity to broader your social circle.

There doesn’t always have to be a big fall out for kids to end friendships, it sounds like they have grown apart with your DS being very young for his age and Mia preferring to hang out with a different crowd. It’s not uncommon for pre-teen girls to feel like they have to start acting mature at that age and there isn’t as much pressure for boys, sounds like she sees your son as uncool and probably felt that she had to distance herself from him to fit in with the other crowd of children. Maybe it could have been resolved but obviously you then got involved with her Mum which was never going to go well, obviously her Mum was going to take her side, you should have spoken to the teacher in the first distance before it all escalated.

As a teacher, I have seen this happen most commonly in year 7, usually between girls. Mía has decided she wants to be part of “the cool gang” and needs to sacrifice her friendship with your son to join. As she doesn’t have the emotional intelligence to tell him that she no longer wants to hang around with him, she has resorted to ending the friendship in a really mean way by forcing him away by bullying.

They seemed to be your friends but sad to find out they aren't very nice people.

Focus on encouraging new friendships and explain to ds it is Mia's loss you, it is sad but he deserves better.

The natural maturity of different children really stands out from age 10 and it's a very normal time for friendships to fall appart. I'm sorry this happened it happened to us too my daughters friendship group of 5 girls jusy fell appart and there was no recovery. The girls all changed over the holiday and came back to school and just didn't click anymore.

’Mia’ has found a new friendship group with the mean school bully kids and has become one herself. She is saying the kind of thing to your son that these other kids say, Mia is made to feel ashamed and embarrassed to be friends with your son by them, they probably badmouth him too. Mia’s mum isn’t a very nice person if she doesn’t accept that her daughter might be influenced this way, and refuses to investigate it properly or address it.

You have to let it go OP. Kids that age can be really nasty and the worst among them are the ones with parents who don’t address it.

I remember this exact same thing happening to me aged 10! My best friend suddenly dumped me for the cool kids. I was a bit lost for a while but then some new kids joined our school and I became friends with them.

We then went to secondary school and I made a new friend in my tutor and my best friend from primary school felt that i'd dumped her - then I was best friend dumped again around 15!

Moral of the story is that unfortunately this is pretty normal and there's a good chance that you have more of it to come. Mia has changed and doesn't sound like she's really on your ds's wave length any more even if she wasn't being so horrible, so encourage him to find new friends that are. It might take a little time but he'll be starting secondary school soon and then will have a much larger pool of people to find friends in.

V good advice

We had a similiiar thing, except the friend in question turned a group of girls against DD. They made up some quite serious tales, told their parents and my DD wasn't believed as it was the word of 5 girls against 1. DS had seen that they were lying. The parents of these girls were my close friends and accused me of having blind faith in my apparently vicious child, within weeks we were ostracised in a small village, DD was labelled as a trouble maker at school. It was an awful time. We fortunately moved away (not for that reason).
Years and years later, DD found herself sitting next to one of the group on a bus. The girl admitted she felt bad about what had happened, her home life had been awful at the time and she ended up in foster care - none of us had a clue. She had been too scared to go against the ringleader and have her school life made miserable too.

I often read threads on here, where mums are told their child must be lying when a group of other kids turn against them and they are the lone voice. But after our experience I know this isn't always (often?) the case.

YANBU, although the teacher handled it very well I think. It wouldn't have been appropriate to have a meeting between your son and his bully as if it were a mutual falling out.

You and your DS just have to accept that some people are fickle and nasty, and it sucks. You have to try to pick yourself up and find other friends who aren't in Mia's "cool kid" clique. Not that you'd probably want your DS hanging around with the tryhard rebel types - they're dickheads at 10 years old and will probably still be dickheads when their own kids are loitering in the local park swearing!

100% this! ⬆️

Some parents find it very hard to accept that their dc are not perfect. Sounds like Mia's mum is one of those.

Not much you can do but widen your friendship circle.

Mia has behaved badly but like many children. It's not uncommon to indulge in a spot of childish bullying. The school was right to come down on it like a ton of bricks. Bullying must not be tolerated and a "friendly" chat isn't the right way to deal with it at this age. That said, Mia is still young and so this could have been dealt with without too many problems had all the adults been on board.

The problem here is the adults. Mia's mother has facilitated her in bullying your son. If my DS was accused of bullying, I certainly wouldn't be burying my head in the sand because I'm not a deluded parent who thinks my child can do no wrong.

Your priority needs to be (and is, I'm sure) your son. I'd just be telling anyone who asked that Mia was bullying your son and her mum was ok with that, hence why you're no longer friends.

Can you encourage your son to explore new friendships?

I'm not meaning here to make sweeping generalisation just from my own observations. My kids and youngest nieces and nephews gen, I've seen how the girls tend to make new friend groups as they get older and may stick with 1 or 2 older friends into teens, whereas the boys are all still in their big friend groups from primary with a couple of new additions from secondary (normally with a sport, musical instrument or video game common interest)
It'sgood to have mixed sex friend groups, but for the sake of your son maybe suggest extending friend group to other boys too.
I've always put it down to differing rates of maturity

Totally agree with all of this. This was my approach. I give gentle guidance but don't police friendships.

Friendships change. An adult friendship that was totally dependent on the children's friendship was always a vulnerable one.

My best friends son and my son went to infant school together, they walked to school on the first day hand in hand. Then never played with each other again at school . We are still best friends, we didn't try and force friendship on our children

I feel like you need to watch inside out 2. It sounds like she decided he was part of her childhood and she wants to leave all of that (and him) behind.

IMO nothing good ever comes from going to the other mum. I would have had a word with the teacher about the mean behaviour from Mia and then explained to ds that people change and friendships change. Then I’d distance myself from the mum.

i know this is no help this time but it might help if a similar issue happens again

Wholeheartedly agree with this. Of course its hurtful but this is very common with young kids and her mum does not sound like someone you want to be friends with if she is enabling bratty behaviour like this in her daughter.

Agree with PP, you have not lost a "good friend" you've lost a "bad friend" and if this is how she behaves her daughter is only going to become more bratty as she gets older.

Chalk this up to experience and model to your son that just because someone behaves like this it isnt the end of the world, he can absolutely make new, better friends who will treat him well. Its far better he isnt around kids like this anyway and part of developing healthy boundaries is to recognise when someone isnt treating you well and to not just blithely accept that.

At that age, friendships change. Puberty strikes some sooner than others. My ds' best friend suddenly started showing him pictures of naked girls. Ds told him not to, that he wasn't interested, and the friendship ended.

There's nothing you can do to turn the clock back.

Aged 5 - 10 is a huge length of time to be "best friends". Kids change. Friendships move on

I was always careful not to openly criticise my children's friends, knowing that whatever I said might be repeated

My line was "at your age, people are still working out how to behave and how to be good friends to people. I encourage you to focus on spending time with people who bring out the best in you and you feel good when you're with them"

Also, I think you have confused "mum of my child's friend" with "friend in my own right". In the past, I spent lots of time with my kids' friends' parents, really enjoyed their company, but when the kids moved on, the friendships with parents drifted. And, that's OK

So, in your shoes, if a similar situation arises, I'd probably encourage DS to let Mia drift and focus on finding new / better / other friendships, rather than trying to salvage an old friendship with Mia that's run its course

Of course it's very common

I don’t think the mom was your good friend to begin with. She was just a school mum friend

You haven't bothered lost osw friends though. You have both lost bad friends. Use it as an opportunity to teach him what a friendship shouldn't look like and it will stand him in good stead.

Have you posted all this before?

If not it must indeed be a common problem, right down to the exact behaviour of the friend's mother and the reactions of all concerned.