"Your memories and feelings say Cassian is your cousin and you don't seem to mind that." Jyn should presumably stop pushing, but Poe says he's in love with a woman he doesn't even know and maybe there is something there she can relate to, regardless of the fact that she'll never admit to anything.

And yes, he is admitting this to Cassian, but at least Jyn is monumentally less talkative than her ...friend, it may take sometime to come out.