I'd love to always, but it IS her mouth and i have to be a gentleman and ask. "M'lady, may I hump your mouth and cum inside, or unload my seeds all over your wonderful face, OR pull out and ejaculate onto a paper towel, wiping my penis with no mess? Which would be your preference----aside from not getting preg. We know that, and prefer your mouth anyway. A win-win. Arrrrrrgh"
That sounds good, as long as I say it in a playful, fun way; maybe like a pirate? Yeah, the main difference is that when I get on top of her, it's simply going in her mouth instead. I get pretty close to the headboard and hold on to it for support while I'm humping. I'm going to try having a paper towel right there when I withdraw it (before I can't stop) so there's no mess, unless she wants/asks for a facial. I can wipe my dick right away too. This should be the perfect compromise.
I climb on top of my wife (from the front) when I'd wake up in the middle of the night with a full erection, pre-cumming and start humping away with her using her tongue. She didn't want me to cum in her mouth so I withdrew my dick at the last second leaving a mess all over her face, hair, erc. I'd wipe my dick on her nightgown. She'd complain sometimes but I'd remind her that's what's keeping her from getting p-------. She'd say, "that IS true!"