Oh I had this. My boyfriend (of 4 years by the end, what a waste of time) used to have Christmas get togethers without me. He used to make a fuss about coming to anything I organised, even just drinks with friends but never included me in anything.
I could understand not wanting to meet his family after 6 months, although personally I think that's plenty of time to know whether this relationship has legs, but not being included with his friends is not on.
My ex used to have a great big family meet up every Boxing Day. After the first two years, I used to beg to come. I loved him, I thought the relationship was going places. I wanted to meet his grandparents - I pointed out that if we ever got married, they would be complete strangers at my wedding, and I wouldn't be inviting strangers to my wedding (that was not my best move, admittedly). He simply wouldn't let me. He literally told me that he didn't want me there, I didn't belong. Why the hell it took me another two years to fuck him off I have no idea.
Don't be me. If he isn't including you then he never will.
When my ex told me his grandfather had died (we had split by then but still friends), I callously said that as I'd never been allowed to meet the bloke, it meant nothing to me. It was a nasty dig, and I'm not that sort of person at all. So don't become me, and turn into some nasty bitch. Fuck him off now and find someone who wants you in every corner of his life.
My now DH couldn't introduce me fast enough, and I knew that he was serious.