with some guys meeting the girlfriends family is a big issue. it can be for several re sons like.
i also had a boyfriend who was scared of meeting my mum. I'd been with him for a total of 3 years and he still didn't know my mum! he'd make up excuses why he couldn't come round to meet her. We used to argue as i knew he was lying to me. Eventually he ran out of excuses and just said up front that he was nervous about meeting her as he wanted to make a good impression and that the thought of meeting her felt like cementing our relationship.

you have to talk to him to understand why he's avoiding meeting your family. it's not fair having a one sided relationship. you are a partnership so he has to give too. Eplain to him how you felt when you first met his family and friends!