No fair messing with a guy's head.
In other words, "no means no" now because it's out of place between them now, but it could ONLY become a "yes" if discerned with Catholic clarity and in context of how God intends life to be lived between a man and a woman.
Kelsey could be the instrument to bring this young man's understanding to align with God's will without compromising herself, and not completely turn him away. He must do it freely; and, he must do the work. She must be willing to help him get it right.
It's up to him to seriously have a major life view adjustment, if he wants to have any chance with her. As long as he resists or rejects it, she must keep pushing back with a "no" - not under these circumstances - but "possibly" with the proper ones. This takes a strong woman! The odds are against her really. Would she find him worth all that sacrifice and self denial, while others more properly disposed may go by? She must be strong!!!
He will realize that he is not getting sex the wrong and shallow way, simply because there is much more to procreative acts than what he currently understands. Such men are seldom interested in really doing all that work and commit to the Catholic way of living.
However, once men really do get this and they commit to the Catholic way, well, it's a beautiful thing! Same goes for women, currently otherwise disposed.
So, as long as she does not redefine the reference or the context from that which I originally stated, and she sticks with the word and the deed, she will be fine. And if he wants to get it and much more, he will just have to close the obviously glaring gap and act and commit to the Catholic way of living.
Too complicated? Unwilling? If one says yes to these last two questions, then the only real leverage for Kelsey, or those in like circumstances, is to walk. No compromise; no "sampling" along the way.
I know this is possible. I think it's similar to a situation that my oldest had. They liked one another. Rules and expectations were made plain. Their hearts and intentions were true. the blueprint or script, if you will, were stuck with. He went through RCIA and converted, and then committed. Now, they are newlyweds :) I have a few pictures of them posted on my profile. I wish them a lifetime of happiness together.
I think that a "no" becomes a "yes" when the woman compromises true Catholic teaching and violates it in practice. She makes mockery of the faith. That is a no-no; it's a sin when done.