You're seeking to get an aphrodisiac/good feelings/serotonin/oxytocin/dopamine potion "for a friend" and the witch starts to smooth talk you into the wonders of her product
Indeed, she has the wonderfully bewitching powers of magic, herbalism and hypnosis at her disposal and you're soon completely caught up by her words and the incense that was burning in the room
Through advanced sales technique, you are persuaded to sample a lick of her love potion
You fall in love with the witch and have good feelings for a while, until she gives you the antidote and you are sent on your way, having purchased more than you intended going in...