I totally get that!!! I need my time, but I'm finding that I need my friends. As I get older I'm enjoying my friends more and more. The more vulnerable I am (and still don't disclose a ton) the better response I get. The more I give to friends (a select few) the more I get and the deeper the relationship. What is cool, is the deeper the relationship, the more honest I can be. Like, "I need a day for M.." Or, "I've got to spend some time doing ... but I'd love to get together next..." A good friend's response should be, "Right on, you take that time!"
Good for you for calling your friends in the mean time!!! When I start feeling lonely, I reach out: call, email, set up a fun outing. I did NOT know to do this for the first 35 years of my life. I really didn't know how.
I do know now that I can be friendly, interested in others AND reserved. I'm not easy to get to know, but I don't want a ton of friends and those that take the time and *I equally take the time to get to know them* I get to form a true connection. I don't mind my "invisible wall" but I think this trick is knowing when it is right and good and when it's not serving M..