Are men and women supposed to be monagomos? Is there an age limit on monogamy? I do believe that anyone who has a clear mind which is not blurred by addiction or obsession can easily accomplish this. But whether young human beings are supposed to follow this way of life is another matter, it appears to have become a growing issue in the 21st century due to sex becoming more acceptable for young people to explore and discover their boundaries.
History tells us that before the Classical theist God came about, love and sex were not connected at all. Sex was just a physical and highly pleasurable act, anything was acceptable; love was an entirely different and unrelated thing. Concerns over pleasure, passion and action presided over this love business.
So following centuries of sex being repressed, labelled sinful and wrong; are we now simply being released from those chaste chains? To the extent we are maybe being over indulgent? Maybe eventually we will calm and find a more sensible approach to our bodies urges and given freedom. For now it may be a little while before the majority of the sexually active population learn to use protection and contraception.