Shani is not a true MC, she is a point of view character at best. One that we can guide into some actions, but there is no "My Shani" in the same way there is a "My Zaton." She is a set character like Aine or the Queen. Zaton can influence their actions, but they are their own characters. And so is Shani. The fact that "Your Zaton" may not have returned Shani's feelings does not mean that in your game she doesn't have them for him. If she were a true MC then Zaton is basically cucking her the whole game because she does feel jealousy about him being with her sister Aine. Just look at their interaction in the main room of the house where Shani almost chokes Aine on Zaton's cock.
Besides that, my main point still stands, having sex in the zone is just out of place. We just saw a guy die because he was having a conversation. Everyone she would run into in the Zone is a best a concern that needs to prove they aren't a threat. And danger lurks around every corner. The very air and land can be fatal... but sure, she could meet someone, trust them enough to bang within a few moments, and just hope a pack of mummies or the raiders we know for a fact are looking for victims aren't walking by. Not to mention she has a clear mission. The Zone isn't a place for her to hangout in and explore and make friends. It's a place to go into, get what she is after, and then get home, thus proving she has what it takes to be a Stalker.
It is highly likely that she will meet someone (probably the female we saw a brief glimpse of), they will team up, probably killing some mummies and maybe even a few raiders, and she will likely need to choose between saving her new friend's life or completing her mission before she leaves the Zone. It would fit with the help/selfish points the player has been giving her, that will likely be used for the outcome if the player skips her content. And if she saves them, they may come back with her, and something could come from it later down the line. But the Zone is no place for sex, it'd be like two soldiers in a trench in WWI banging when the enemy could rush the line at any moment.
Maybe I'm wrong, and a sex scene will happen in a way that makes sense give the context of the Zone... I won't see it because I'd have her turn anything like that down, but, we'll see.
Edit: Also, in my post I did preface my statement with "dangerously close to," and "basically," as I didn't want to make a definitive and declarative statement since it was hyperbolic in some ways.