marriage/ sex

So me and my husband have been together going on 10 years and married going on 5 years. Sex has always been great ever since we started having sex. We have tried new things like anal, toys, and positions. But he has really been pushing the issue of him finishing on my face, in my mouth, on my lips. I'm just not up for it. It's not something I have ever really wanted to do. Does anyone have any advice on maybe easing into it or something. Or if it's normal for me to feel this way about the topic?