I'd keep them separated until he's been neutered and his hormones reduce a little and have a wellness exam done on him and mom. There could be a medical explanation for the bickering if one of them is ill so it's best to rule that out first.
The other thing...
From some reason we humans always tend to think gliders are mates for life, and are shocked that after 3 or 4 years of getting along, n raising babies suddenly they don't like each other, start fighting even injuring each other.
They aren't naturally mates for life.
The domestic gliders just can't do what they naturally would in the wild. in the wild when this happens one of them would voluntarily or involuntarily go find another colony. Caged gliders can't escape their mates, all they can do is fight and hope the human recognizes it and intervenes. This isn't just for breeding pairs this is any gliders in colonies in cages.
Things change, dynamics in the colony change, we humans need to recognize those changes and be prepared to make accommodations when we see those changes.
I've had to move gliders around a few times. Currently everyone is content with their cage mates but that can change at any time.
Sometimes it's also just a cue that they shouldn't be breeding anymore.
It could be one or all of these things or something else entirely, so we really can't say