This is all because for guys, it's "more of a social stigma" if they "don't have a girlfriend" or "haven't had a girlfriend" and are "still virgins" and so the like, thus they attempt to get into a relationship as soon as possible with pretty much the first girl that looks attractive. Later on, it's probably a result of desperation - they're willing to take the first that comes by.
I personally would prefer to see the skeletons in the closet first before I'd settle by a person, because if something's unacceptable, I'd just rather leave it. Such as smoking weed, excessive partying/drinking, conflicting values, etc.
So to actually make this post worthwhile, it's a result of stereotyping of the opposite gender. People often are swooned by the fact that the other person is an "attractive girl", and forgot to actually get to know the individual themselves. It's a shame, really. Once people realize that the social pressure is nonsensical, and that there is more to others than getting them laid - this no longer happens.