I Think I'm Turning Hikikomori

It seems that the older I get and the more I have to deal with the rest of the world, the less I want to do with it. I used to live for social situations; I played sports, went to parties, clubs, concerts and community events like it was my job. It seems, however, that over the past few months I have become more and more content to just stay at home, sitting in my room watching television or reading. At times, its almost as if I have to force myself to go hang out with even a small group of friends. Some of my friends have inquired as to if everything is okay, and I'm quite sure it is. I eat healthy, I have an excellent relationship with my girlfriend, and I honestly feel that this is one of the happiest periods of my life. The fact of the matter is that, for the most part, I simply don't like being around people very much anymore... And I'm happy with that.