Relationships established in the Internet tend to be much more detached and impersonal, simply because you are not directly interacting with the individual. What differentiates a conversation occurring on a social media website and one taking place in person is that you are not observing the body language and mannerisms of the person you are speaking with online. Rather, you are conveying the message you want to say through words alone, rather than with any body movements to enhance the meaning of it.
I suppose that it is easier to talk on sites such as Facebook for many people although due to the fact that is less social pressure and greater freedom of expression, without the presence of nonverbal communication to bring about any confusion or misunderstandings. I personally believe however that relationships established face-to-face tend to provide greater intimacy and trust.
While social media sites do provide a great way to keep in touch with individuals you otherwise may not always see, they are often lacking in the depth in connection that comes from physically being able to observe the other person and changes in their behavior.
If you want to improve your social life however, then I suggest that you simply try devoting some time to doing something with a friend ever so often, such as doing an activity together, but balance it out with your need for alone time to recharge every now and then. It is perfectly normal to demand your space from other people on occasion, but becomes unhealthy when you begin isolating yourself from humanity and refusing to interact with anyone at any given time. Remember too that it is neither healthy to “detach” too much from people, or to “attach” yourself excessively to them; there should always be a give and take in every relationship.