Your every post is an attack on women, they are not to be trusted and only get married to "get rich quick" among just a few of your post.
It's a cavemen originating thing.
10,000 years ago he wanted to have sex and she too, but she also wanted a big peace of ham or a nice bone necklace - plus additional protection towards those wanting sex but not offering a compensation in return.
Today he wants sex and she too- and on top she wants an I-phone or his wallet - depending on the neighborhood she lives in, sometimes also protection.
Religious imposed morals and thus education - tell the man, you need to get married to safeguard the woman's reputation and to take responsibility for the child that might result from your act.
Religious imposed morals and thus education - tell the women, you need to get married otherwise society will term you a slut and you got no financial safeguards for a possible child.
Most man simply don't want their girl to get laid by another guy - and vice versa, so both seek security via threats (e.g. I will leave you, I will beat you up) or marriage
One part has been solved mostly thanks to little silicon gadgets (some even with flavor and nobs added) and the pill.
The other part has been solved by society via paternal lawsuits and thus resulting in legal $ obligations by the man, or the government has to come up with the $.
In today's world anyone performing sex without a preservative must be out of his mind or a religious nut - unless he/she has solid-reasons to believe that he/she is "loyal" which according to divorce statistics proofs to be an utter miss-believe. Therefore in our present society only the "slut" issue remains, and the "I don't want her/him to have fun with other hims/hers
Oh yes there is actually something termed "true-love" - factually occurring only in the initial stages of a partnership and usually as a precursor to sex - radically loosing out as life progresses. - see divorce statistics.