Classmate staying over constantly

My partner is a graduate student and has a classmate that lives quite far away from school. My partner has offered the classmate on numerous occasions to stay over after late night study sessions so they do not have to commute a long distance, typically the night before exams. However, I am starting to build resentment to this classmate as they are now staying over close to once a week. They don’t make a mess, but they don’t leave my place as it was either. I often find myself feeling forced to make them dinner. I don’t want to be the bad guy and say they can’t stay anymore, but I really need my space back as we live in a one bedroom and when they stay over, I feel confined to my room. Also, to be honest this person never really does anything nice for me despite my hospitality. I hate to sound selfish and expect something in return, but it just seems weird that they would never do anything for me to thank us. Plus, we pay expensive rent to live by campus. What should I do?