The stage at which a person loses the choice as to whether (s)he drinks alcohol or not.
Once this condition is reached the person concerned will inevitably drink too much alcohol as the reason for losing the choice (through addiction) is because the brain thinks that alcohol brings pleasure or a release from pain (one and the same thing in effect). As human animals we will always chase pleasure, which equates to an improvement in survival. The person will go on drinking more until the equation (drink more=more pleasure) is turned around to drink more=less pleasure (through immediate pain for example).
When the brain has forgotten the pain drinking brings the binge (in the case Jane my partner) starts again.