Ummmm, I think your statement would be more accurate if it said, "Some guys develop unhealthy attachments and infatuations really quickly". I had a good friend in my early twenties like this, all it took for him to be "head over heels" in "love" was for a woman to pay attention to him for more than just a couple of minutes.
IMO people that latch on emotionally that easily are seeking to fill a void (highly likely it's unintentional) in their lives. Invariably this is a recipe for disaster since usually these same people will allow themselves to be a doormat in order to keep the object of their attachment.
Correction duly noted.
And I agree. If someone falls that quickly, the love doesn't run very deep, it's more a symptom of that person trying to run from something else in their life. Using someone as a crutch - even if they end up truly loving you, is unfair to the other person.
I'll go far as to say I've known more than a few guys who look back and say "I knew when I met her she was something special", but I don't recall ever hearing a guy say "I knew she was the one that very instant."
I guess where I was going with this is It's been my experience that a lot of guys will become a lot more interested in a woman sooner than she realizes, and sometimes they will do so faster than she herself becomes interested. This can be a good thing as it drives a man to continue onward, but if they aren't balanced and they let that drive consume them, then bad things are going to happen.