Perhaps he is still deciding if he really is in love with you..? Maybe he doesn't feel sure yet. You can't pressure people to act a certain way.

The feelings arnt mutual

you haven't met any of his friends and family is because YOU are the OTHER woman.... he's not let you into his life, because you are not part of it - you are his booty call. You been played.

Run. Run as fast as you can away from this guy. If he hasn't introduced you to any of his friends or family after six months, or included you in his life in a meaningful way, it's a huge flapping red flag that he is compartmentalizing your relationship because he has a wife or girlfriend, or because it will be easier to discard you when the time comes and he move on to something better.

You won't change him. He has you sucked in, thinking about him all the time, and I bet waiting for the slightest bit of acknowledgement. And I also bet there are also a lot of other red flags if you let yourself see them.

Life is too short. Cut yourself loose so you are free to find someone who truly appreciates and cares for you, and wants you in their life.

...as far as warning signs go, your "boyfriend's" reluctance to introduce you to family, even via FB, is pretty hard to ignore. Have you met any of his friends? Have you been to his place, or do you only meet at yours? Maybe dial back the whole " I think about him every second" until you can be certain he isn't misrepresenting himself.

I might be wrong as I don't know either of you but usually this means that he already has a girlfriend. Some people can be very private or take much longer to feel comfortable mixing lives together but at 6 months I would have expected to meet at least one friend. Also when I last dated someone (for 4 months) I didn't introduce him to my friends because I had already decided that it wasn't going anywhere serious.

You sound very young and infatuated. My advice is to talk to him about it. Meanwhile try to have your own life - it isn't healthy to be thinking about one person so much. Unless it is yourself. It may be this intensity that is keeping him from bringing you more fully into his life.

Does he have friends and family? Some people don't have one or the other.

Congrats, you're the side chick.

...who has always compartmentalized my relationships. It has been extremely rare for anyone I've dated to meet any of my friends, and my family members are all far away so that has never even come up. I've never added anyone I've dated on fb, even if they've tried to add me, because I like to keep my life in neat little boxes.
And now I am - unexpectedly and delightedly - in love with someone. I have met most of his friends, and we are "friends" on fb, and in the next little while he will meet some of my friends in real life. It is challenging for me, but I am crazy about him and for the first time I really want to integrate someone into my life. I'm willing to take the risk because it's important to him and because it feels right.
So maybe the guy you are dating is a compartmentalizer because he is trying to protect himself. Or maybe he doesn't see a need to integrate you into his life because if your relationship ends, that makes it neater and easier to move on. Talk to him about it. You might not hear what you want to hear, but he also might be willing to take a chance and do something outside his comfort zone if he really wants to be with you.

but you are not his girlfriend.