Where would the Ghostbusters be without the ray of sunshine that is Janine Melnitz? We joke: for most of time this nasally New Yorker either seems bored by her job as the Ghostbusters' secretary or complains about being overworked.
You can't really blame her, though.
When she first gets there there's nothing to do because there's no business, and after that she's swamped with low pay and no time off. There's not much Janine can do about it, though, as Venkman reminds her,
PETER: Janine, someone with your qualifications would have no trouble finding a top-flight job in either the food service or housekeeping industries.
Janine may not be over the moon about her job with the Ghostbusters at first, but we do see her light up when the business first takes off, showing that she does care about they guys and their mission. Of course, the guy who she really seems to care about is Egon, who she shamelessly flirts with for the entire movie.
Unfortunately for Janine, Egon isn't interested and even at the end of the movie, the most she gets is a pat on the cheek from him. Janine will just have to wait for love until Ghostbusters II when (spoiler alert!) she'll date Louis Tully.