To be honest both of you could use some attitude shifting.
I recommend to YOU to approach giving head as an exploration. Get in the moment, don't do it to please him... just stop. Do it because you want to, even if it means less often. Then only do what you enjoy doing. Get into a comfortable position. Explore it, the texture that taste and sensations and fully absorb yourself in the moment and enjoy it's responses. If you don't like come in your mouth don't have it come in your mouth.
I recommend to HIM to get over his fantasy. If he wants you to LOVE giving head, then allow you to do it in a way that is enjoyable to you. Your enjoyment of it will increase over time as you do it on your terms, as opposed to in a role of "fantasy fulfillment" for him. You may or may not end up loving him coming in your mouth, but as you do it on your terms and again, with the approach of exploring his body and enjoying the sensations and textures and for only as long as you are comfortable... you will enjoy it more.View Thread