ew god, it's because you call it an "encounter" and you keep a time card on her. take her out, get her kinda drunk, and say some naughty things in her ear in public. c'mon. the grossest, absolute grossest thing you could do, is to have a serious discussion about why she isn't putting out, and get all clinical about it, and put it on her to please you as if its her responsibility. just be cheeky and fun, and mellow out.