There was a child in my son's class who was a complete nightmare for various reasons. It disrupted the whole class and impacted the other kids, including nasty and violent behaviour.
DS and his friend ended up getting the worst of it at one point.
Mum was in complete denial about the whole thing. Kept saying 'hes only little', 'its due to him being premature, he'll catch up' and 'hes the youngest in the year he just needs a bit more time'.
We could all see there was a massive problem even at nursery and it only got progressively worse.
It all came to a head in year 3. He was terrorising the class. On one occasion I know he had another child by the throat in front of parents. Mum just laughed and did nothing. The other parent was in shock and rescued her child from the situation and was overly polite about it. But this type of behaviour was normal and constant.
We weren't. We went to town with the school on how they were not safeguarding our child and how they were failing the other child because it was clear there was a problem and he needed help.
I am aware that the other family ended up with social services involved which they didn't like because they were middle class. But Mum was still in denial, and still unwilling to do anything about it saying 'he'll grow out of it'.
At this point Dad had enough and the relationship nearly broke down. Mum was pretty much given an ultimatum, to start engaging and taking it seriously or they'd break up.
Mum made the decision to go with it. The child was put on medication.
The difference was like night and day. He still was difficult and acts up, the level is much lower and more manageable. All the other parents noticed too, and I think there was this collective sigh of relief in terms of not worrying how you were going to deal with the next round of issues created by this one child.
The moral of the story is - don't be the parent in denial. Be proactive. If the school are saying that he needs further support, he needs further support. Bite their hand off for it - budgets are tight and they won't be saying this if there isn't an issue. Find out what the problem is, read up, start fighting for what support he needs.
Failing to do this will lead to isolation and embarrassment and a world of new problems which only get worse as your child gets older. They won't 'grow out of it' without support and intervention because they are caught in a cycle of behaviour and they don't know how to break out of it. A five year old kid doesn't have the capacity to do this alone. A five year old kid acting up to this degree isn't coping with the environment. The other kids understand the expectations placed on them - why isn't he responding in the same way to the normal rules ?
If your partner is in denial, that's one of your battles. If you can't get your partner onboard, then you need to re-examine the relationship because your son needs you.
The parents of the kid I know are still together but I know it's not unusual for couples to split over one being in denial.