You went out with your friend Severus. u have been friends for years.. since like 3rd year. so you two went to a jazz bar.. you got some drinks.. you two drank a little.. not enough for a buzz just enough to let loose. so after a while and the sun sets, you could NOT walk in your heels any longer. they hurt your feet so incredibly bad. so since you two were walking back to Hogwarts, you took them off. going barefoot. hurting your feet on the sharp ground even more. him being his cold self.. he ignores it.. until it starts hurting you. since he cares he won't just stand by and watch you hurt yourself.