My partner actually used to do something very similar.
after a lot of therapy and discussion we established that it was due to childhood trauma.
feeling criticised or like I was saying they had done something wrong sent them in to an absolute shame spiral that they just couldn’t cope with so emotionally withdrew.
partner often described not being able to control it in the moment.
HOWEVER, it would last a few hours at most and my partner was able to acknowledge the huge impact it had on me /our relationship.
partner went to therapy and actually ENGAGED in it - and once they had understanding of what was happening (and I did too!) it became easier for them to communicate with me.
your partner may/may not be having the same kind of experience but what they are doing is actually very abusive insofar that they aren’t willing to do anything about it (!!!) and are not acknowledging the impact it has on you/your kids.
six weeks not speaking to you is actually utterly insane.
it will not change unless your partner wants it to and is willing to put in the work.
the reason underlying the behaviour is not your partner’s fault as it probably is related to trauma/ND HOWEVER, them not addressing the issue is absolutely their fault.
Also, you don’t have to keep putting it with it if you don’t want to. You can leave and would be well within your rights to do so after years of this behaviour.