Honestly, there's no right or wrong here - it's what you're comfortable with. Some of us have to move toward physical intimacy at a snail's pace (myself included, as physical and emotional intimacy are all tied up together for me), and others prefer a faster pace. I suppose it all depends on your attitudes toward sex.
Whether she's being naive or not, in my view, is irrelevant simply because her decisions are her own business. You may be right...the guy she's with may be a total player, but there's little anyone but she can do about it.