my partner is a drinker and thrashes wildly and shouts outs and swears when a asleep sometimes forcing me to sleep in the spare room why does he do this
He is having withdrawal systoms from the lack of alcohol in his body.
It's colloquially called night terrors, alcohol may be messing with his brain, what you are experiencing is (it may be hard to believe) a fairly mild case
I think you will find your wrong about this, as having researched this and with working in this field I can assure you he is having withdrawal, as if he was to awaken and drink some alcohol he would sleep perfectly.
Regards.
Withdrawing or not this ladies partner is not dreaming he's having a picnic of tea and scones whilst flailing, thrashing and swearing in his sleep