With Sharon I can agree seeing as she was already cheating on her husband and had no problem not only putting out for you the first time, but continuing to do so if you choose to protect her. Jet however not so much. her story was that she didn't want to even get involved with this, but because she was being blackmailed by Warren she needed to do it for the money otherwise she would be dead.
With Rachel is there Romantic tension? Ye I can agree there was some. However at the same time unlike Sarah she had no jealous nature and as I pointed out just wanted to be seen as the most special of all to him. Add this and her messing around with her other best friend and we got a somewhat romantic but still open best friend.
Sarah on the other hand as you pointed out not so much. She got extremely jealous when she thought of the main male looking at other women and we saw this several times (Jet at the hospital, Shasha when she as sucking you off) however despite everything done on both ends to cock block (MC at the party with the sink bomb, and Sarah during the date) You can easily end things with Sarah by choosing her friend Shasha. Not only will this remove the oh so unpleasant taste of the brother stealing his sister's cherry and ruining her for other guys if they did end things (cause as you pointed out he has the biggest dick in town and no one would be able to sate her after he ruined her) but at the same time due to Shasha's nature and looseness for all we know she might be much more open.
But this is once again assuming you choose her.
Well yeah we are assuming you chose sarah. Choosing shasha is a different universe, we can discuss that universe but it has nothing to do with the brother sister hookup universe. Lets say you get all content done and chose sarah. How many pussies can you smash in recess again? How would sarah honestly feel if she knew what a manwhore her brother was, all while progressing with her and at the peak of their relationship? It would break her heart, thats why brother is a piece of shit who doesnt love his sister.
With rachel the romantic tension comes from the long wait to put out. You have to date her and progress your relationship to get to that level. Doesnt smell like an open relationship to me, even more so considering you took her V card and she was your best friend. Yeah she might be okay with just fooling around and having fun, but we dont have enough information at this point in the content. What we do know is that she loves MC, gave him her v card (once again), and to me this suggests that she wouldnt be okay with you banging everything in town, only using her when you got bored of all the other puss you were smashing.
I would like to see rachel catching you with another women and seeing her reaction. She hasnt exhibited any signs of jealousy because there hasnt been any situation where she should be jealous. The content is very limited, when you complete rachel you can return whenever for a repeatable scene, even if its a month down the road, and thats it. I think it could go either way myself, but it would make more sense for rachel to get jealous and ask for a commitment in my mind, even with her hooking up with her best friend behind your back. 2 chicks experimenting hardly qualifies as cheating. Another man isnt fucking her. There is no chance for pregnancy. There is no competition. ectectect
With Jet yeah she really appreciates what you did for her. She does like you. She likes that you seem to actually care about her and risk your life for her, something she hasnt experience. But she has been around the block (bigtime), and I doubt she would have a broken heart if she knew about other chicks, or have any problem moving on if you dumped her. She is a strong chick, and she didnt ask for a commitment in the first place. It would make a lot of sense for her to just continue banging you even if she found out about other girls. She gets it.
A side note about jet. I think she is bad news personally. She was a gold digger who tried to get away with inheritance after her sugar daddy croaked. When she used her girly charms to tell the story, the entire time I was thinking she was a liar and I wouldnt be surprised if she poisoned the old bastard or something. Smells like a lying manipulative whore to me, but of course she batted her eyelashes and shed some crocodile tears and off PC went to break into a mobsters hideout.