I don't think is the only "It" but it's certainly one of them - the underlying subconscious belief that if he's into her she must be into him too so he just has to perform being a "good date" and show her that he likes her and all will go smoothly. Meanwhile, she most likely wants a more nuanced, more connected, interaction where they actually get to know each other and he's actually interested in more than just viewing her as a kind of side-kick who will eventually fall into his bed.