He flinches and his mouth opens at the same time. Attraction. She used the word attraction, and obviously there had to be some level of appeal between them or Rey wouldn't be here, but she is making it sound like a much bigger deal than that.

And it's not one-sided. He's thought far too many times about how beautiful Jyn is to him, several times alone today. If anything, he thought it was one sided on his end.

"I have never made anything of the sort clear, Jyn. I could not have, when I didn't even know -"

Rey lets out a very loud belch and whines loudly about it immediately after. How dare her body make so much noise.