if you want to be happy in life, you are going to have to find a way to get this alone time without feeling guilty or like you have offended anybody. a good thing to do is to explain it to friends and boyfriend just as you have here, but not when they are wanting to do things with you cause then they may see it as an excuse and be offended. wait till such a time that you are together and chatting about yourselves. then bring it up as if it were a quirk you have, like "something people dont understand about me is that i really need my alone time...." add that you dont mean to offend by wanting to be alone, it is just who you are. presented this way, they are likely to be more understanding of your situation. take care