Head in Bed

So every time me and my boyfriend have sex he always asks me to give him head right after , we don't use condoms but I've been on the pill for about 4 years. We try to be very careful. Anyways when we have sex it's always amazing and I cum but when he asks me to give him head it takes him forever to cum. I feel like he's being nice and not saying anything but I'm not sure if I'm doing anything wrong. I've given head once before but this is my first time actual being physical when a guy.