I've lived with my boyfriend for 6 years, but before that I HAD to live alone. I had a terrible experience with a roommate before. Freshman year of college, all students were required to live in dorms to help us socialize.
I had a roommate and about 10 girls sharing a common area. Every day was torture, just having so many people around, never a minute of solitude, not even in the shared bathroom. I was so excited to go to a good school and be placed in the gifted dorm, only to find out I couldn't hack it. They were nice people, but it was just so stressful and exhausting having to navigate so many social interactions and new people without a break. My roommate was very preppy, and after I did some weird stuff (died my hair purple, came out as bi, dated a man in his 40s) she just refused to talk to me. Answered me only with one syllable for months, no matter how nice I was. Like I was invisible. Every day was stressful. We had a few interventions and the RA let me switch to another dorm. I think the dorm system was a big part of the downward spiral that led to me dropping out as a freshman. When I returned, I decided to live alone no matter what, and it helped tremendously. Sure, I probably acted stranger than if I had a roomie, but the ability to have "down time" to recover from socializing was a huge help to me. I lived alone for 4 years, it took a few months to get used to but after that I loved it. Now we live out in the country, and the "isolation" helps me. No half-heard conversations and random people and noise around all the time like in the city. Just Nature.