I LOVE living by myself, and I am never going to live with another adult ever again. I am definitely not half of a pair, or a permanently social creature. I am very much an independent person, and I like it that way.
I like being able to wind down when I come home after long days in work, being able to starfish in bed, being able to be ill in peace (I have migraines...), it is quiet enough for me to sleep without being disturbed (I am a light sleeper), and I never have to compromise (I grew up in a world where I was supposed to put everybody else's needs and wants first, and what I wanted was irrelevant, and where saying, "No", was not an option). I get to make all of the decisions about my life, and it is a non-stop novelty.
I move heavy furniture by myself, much to the shock of some burly delivery men. I may be small, but I am strong and mighty!
Sometimes it is tricky financially, and huge DIY projects can be easier if you have an assistant/can hire someone who is reliable enough to do the work for you. It might be nice to come home to a meal once in a while, after a long stretch in work (living rurally limits your takeaway options). If I was in a relationship, it would probably be easier to have a child and ruin the idea of any alone time for at least 18 years, but there are ways and means around this!