Usually sharing a space doesn’t bother me but I can understand op frustration — I used to have a roommate who was in the living room all the time and took up the whole couch and always hogged the tv (both of which were mine) and had to be in the kitchen if I was (itty bitty galley kitchen with no room for two people), even with a shared space it is nice to be able to sit on the couch/cook a meal by yourself and some people just have no awareness that they’re hogging space