Not sure how true this will be, given that Luna is really devoted to Aidan and all her actions, including sexy times with Vargas, are all just to serve the purpose of getting the formula to cure Aidan. Luna is just saying that stuff that Vargas wants to hear so that she can get closer to him to finally get that cure. Think of a femme fatale who pretends to be close to the bad guy to get info to infiltrate the inner circle. She's not falling for Vargas. Rather, she's just buttering up his ego so that he'll lower his defenses around her.