Great job building tension!
Review written after reading 11 chapters:
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Overall, I think this is awesome. You have done a great job of building up tension between Fi and Alexis, and the scenes between them are super hot. I think the dialogue is realistic, the characters make relatable choices, and the plot is coherent.
I have two comments about the writing style that I think could improve the story even more. The first is that you have a lot of short sentences, and sometimes short incomplete sentences. I think this is a great tool to indicate urgency and breathlessness, but I think you are over-using it a bit. If you play around with the length of your sentences, then the short ones will really stand out. It's like how if you emphasize everything, then nothing ends up more emphasized than anything else.
The second is that you have a few scenes where you describe a particular situation from two points of view. I like it, but I would like it even more if there was less repetition between the two viewpoints. As an example, at the restaurant, Fi described the decor, so when Alexis described the decor again on his turn, I wasn't interested anymore. If you have two people describing the same thing, make sure they are noticing different things about it.
Other than that, I think this story is great!