Having trouble getting off with bf

So, I've been dating this person for a few months and I really like him. We are sexually active and the sex is really fun for both of us, but I'm having trouble orgasming when we have sex. He's been really sweet about it and trying really hard to get me off, but it just hasn't happened yet. :( He suggested getting a vibrator, which I'm all for because those are also very fun, but I want him to be able to get me off too. Any tips on how to make orgasming a little easier?