Dating has only been around for about 100 years, and is (obviously) a complete failure. Dating was actually started by the lower classes, because they did not have parlors or places within a home/apartment for the couple to have some privacy. Working well, isn't it? People start to engage in sexual activity, and they either don't know who they're marrying because they're blinded by the sex, or the relationship does not end in marriage, and both parties add emotional baggage to carry to their next relationship.
I think that's why people are waiting longer to get married: the guys are getting it for "free", so why take on the additional burdens of marriage and family. The women keep hoping that marriage will happen, but get put off; when this happens in their early 20s, they are much less willing to commit in later relationships because of being burned. What a price to pay for sexual "freedom".