Please tell me that, in this context, "last" just means it'll be the last kind of sex we introduce her to, not that it'll be in the last update/at the very end of her storyline, with only one scene. At the very least I'd hope there's a progression from insisting on a condom*, to being okay going raw but expecting you to pull out, to accepting/wanting to be creampied, eventually resulting in pregnancy, with preggo sex as the fourth scene in the sequence, during the ending.
*...wait, come to think of it, do condoms even exist in this game? Now that I think about it I don't remember them ever being used, not even with the girl who gets pissed if you don't pull out, whom you'd think would insist on them.