I think 6 is a particularly crap time, going by lots of other mums I know.

At times like this I try and take myself out of the situation and acknowledge they are going through something. Yes it is impacting you all, but he is clearly struggling with something. Lower expectations and hold him closer. Treat him as you would a child of a younger age. Really lower those expectations around everything and then praise him for any progress. You might want to consider curling up next to him while he is sleeping just to reignite some of those love hormones between you.

Hang in there.