Oral sex questions?...

Every time i give my boyfriend oral he ends up going soft. Now... I don't have a gag reflex. So could this be making him insecure? I feel as if he's thinking too much and isn't relaxing. What can i do to make him feel more comfortable? Could i possibly be doing something wrong? I always get him in the mood & even make sure im gentle and that my teeth aren't in the way so im really curious on what the could be.