My bf just doesn't seem into me anymore

We've been together for a little over a year and he just doesn't seem as sexually interested in me anymore. I used to give him head almost daily and now I'm lucky if i can get his attention long enough for HIM to get off. Idk how to talk to him about it without hurting his feelings or pushing him away and i don't wanna jump to conclusions or be irrational but what if there is someone else? I have no clue what to do anymore. Help :(