Ask her

"Oh God, I am about to cum" I moan, Millie's mouth is full of my dick, so she only replies "mmhhmm..." Not sure if that is enough to communicate the message, I add "I want to cum in your mouth" but she only replies with "mmhhmm..." again. Very good manners, I think to myself, she does not speak with her mouth full.

Millie is not letting up the pace, and I feel my balls tighten up as I am getting close to cuming. Millie feels I am close as well, so moves up to only having the head of my dick in her mouth, she holds her mouth still, while rapidly using her right hand to masturbate me.

With a massive groan, I cum in her mouth. She does not flinch, but keeps sucking until my dick stops shacking and she is sure she has sucked the last of the cum out of it. She stands up, does her best to smile as she has to keep her mouth close as it is full of cum, then walks to the bathroom and discretely spits it out in a tissue.

She comes back, picks up her jacket and bag, kisses me on the cheek, and says:

"Thank you for being a gentleman and asking before you came in my mouth. I am fine with it, but hate it when men just presume that since I am sucking their dick they are free to jizz in my mouth. Plus if the cum is not announced it can easily **** or gag me if the dick is to deep."

"Well, I like to make sure a woman is happy after she blows me" I reply. "That way the chance of her sucking me off again are much increased and it is also the polite thing to do." I continue.

Millie smiles and as she walks out the door she says "remember that this was just a fantasy".