Boar pairs should be kept well away from sows. I see that all your piggies are young and are coming into their teens now. The boys hormones are going to be starting to rise and they will become very interested in the girls - you need to prevent the boys from being able to see and smell the girls.
It’s recommended that if boar pairs and sows pairs need to be kept in the same room, that they are kept either at opposite sides of the room or that they are kept in stacked cages - with the girls living in the bottom cage and the boys living in the top cage.
Stacked cages prevent sow pheromones from falling onto the boys and also prevents boys being able to get in with the girls.
If they must be side by side as yours are now, the divider needs to be solid, opaque and higher and wider than the cage so that sow pheromones don’t drift about to the boys so easily.
The boys cage needs to have a secure lid to stop them being able to climb over the top - which they absolutely will do, young boars are very athletic and will make light work of escaping if they can get in with girls.
Always ensure you handle the boys first so that you don’t risk transferring sow smells into the boys.
I am concerned that you found one of the boys in with the girls. You must put the girls on pregnancy watch now for 10 weeks from when the incident occurred.
If the boys are actually fighting because of the presence of the girls, then the boys bond is at risk. You need to make it so they cannot see or smell the girls otherwise the boys could end up needing to be separated permanently if their bond gets broken.
A Comprehensive Guide to Guinea Pig Boars
