boyfriends girl friend

I've been with my boyfriend around a year and a half, and ever since the beginning he had mentioned this girl who's a friend, amongst other friends he has who are girls. I'm absolutely fine with that, I have male friends! But this one makes me feel uncomfortable... they go to the cinema together every now and again to watch films that to be fair, I wouldn't want to watch anyway. However, it's been a year and a half and I haven't even been introduced to her. I know there's nothing going on, I trust him, but it just makes me uncomfortable that I've not met her. I have just told him this now, to which he's said 'fine I'll stop going' I don't want that, I'm not controlling and don't ever intend to be, I would just like to meet her in a social environment (not the cinema) to be able to get to know her on a certain level.