As you're making arrangements for your stay-in inpatient rehab, ask plenty of questions about how rooms are assigned. In most cases, facility staff will try to match up patients with similar needs and challenges in semi-private rooms, a method that can ensure that there is common ground between roommates that fosters good relationships and mutual support. Additionally, if there are things that you know will be disturbing or annoying to you, such as a roommate with a loud radio or TV, crowds of daily visitors, or a serious snoring problem, speak up about those issues ahead of time in order to give staff plenty of time to try to accommodate your needs.
Bringing a few familiar items with you to make your half of a semi-private room your own during your stay can help you feel more at home and clearly define your space in the eyes of your temporary roommate. Just be sure that you respect your roommate's space too. Lastly, don't forget that privacy curtain is there for a reason. If you're feeling a bit crowded and need a break, use it for a breather.
Being able to set limits in a polite, tactful manner will make working out a pleasant, cooperative, and supportive relationship with your rehab roommate easier. For instance, if you're very tired after a tough therapy session but your roommate is busy telling you all the details of their day, don't be afraid to ask to postpone the conversation until after you've had a snooze. If you're a private person and don't wish to discuss your medical details with staff in front of your roommate's visitors, ask them politely to step out of the room for a few minutes. Of course there will be other issues that need working out, but the point is, don't be afraid to speak up about your needs, rather than keeping silent and letting your concerns fester. Last but not least, encourage your roommate to speak up as well, and make sure that you're working to respect their limits too.
Giving up some of your privacy for a few weeks will be an adjustment. However, for the vast majority of people who have the experience, having a roommate actually makes inpatient rehab easier. Support from family and friends is great, but it isn't quite the same as the emotional support and encouragement you'll get from someone who is in the same boat and knows exactly what you're going through. Chances are, after that first awkward day or so, you'll find that the camaraderie between yourself and your roommate is well worth the price of a little less privacy.