no favor in return

Okay so me and my boyfriend have been together for a year, I'm 18 he's 19. I love him to death and when we spend time with each other i love every moment of it. But every time we see each other I always please him and have him cumming like crazy(We haven't had sex so I only give him blowjobs). I find it very pleasing when I can make him cum and he's mind blown every single time, but he doesn't return the favor back unless I say something about it... he's only eaten me out once and it was AMAZING! I keep asking for him to do it again but he never does. I know it has nothing to do with down there cause I'm clean. But when he ignores my request, it makes me feel insecure... do I just ignore it and stop asking? Or keep asking hoping that he'll give in?