you should tell her you want to set boundaries (sit down with her one and one) and lay out your needs, like having your bf over, and set specific boundaries surrounding your bf (ask if she would be more comfortable if he just stayed for certain time frames, like during the day only, during certain times, etc) also influence her to communicate directly, and communicate EVERYTHING, even the small insignificant things. i noticed that my roommate would bottle up when i was doing little things that
irked her, and that led to a lot more issues between us. you should make sure youre both comfortable communicating and tell her that its okay to feel certain ways in the shared space and to communicate everything, even if its small things because otherwise she will bottle it up and itll boil over (same goes for you!) also just set general boundaries for both of you (expectations for guests, chores, etc) writing them down can help stick to them and holding each other accountable. dont be afraid