There is no Rational reason Not to sleep around? You truly aren't serious are you?
If you are I think you recieved a far less than adequate education.
Lets look at it strictly from a biological perspective shall we? Increased risk of STDs
Increased risk of preganancy and not having a partner around to aid in the upbringing of the offspring.
Increased likelihood any offspring created by this will be raised without a father or father figure.
Vastly increased likelyhood of living in poverty should one become a single mother.
Vastly increased liklihood that offspring will have any number or problems or issues because they don't have a father.
These are all proven facts. Rationale dictates beyond question that women tend to do better by not acting like men sexually.
Sexual promescuity does real damage to people, and removing the emotion from the physical frankly creates damaged goods. I don't know one highly promiscuous woman who is happy with their lives. In fact most bitch to me that they can't find a man, and refuse the simple answer that most men dont want a long term situation with a woman whos been around the block a few hundred times.
You sow your oats with sluts... you don't marry them. That's reality. I don't care how much pop culture may want to convince everyone otherwise, its reality. If as a man you cannot trust yout partner to remain faithful, you find another partner... biology 101. If you can't be reasonably certain any offsprint created are yours, you won't expend the effort, energy and time to raise them.
Increased risk of preganancy
-- not if you're careful with condoms!
and not having a partner around to aid in the upbringing of the offspring. - not a fact at all. In fact, many people would argue, they wouldn't even considered marrying someone they never had sex with.
Increased likelihood any offspring created by this will be raised without a father or father figure. - again, pure speculation. Do I even need to continue? There is NO hard evidence, none. I know plenty of happily people, who see no problem with sex before marriage. That's not my idea of right behavior, but i have different foundation as we already discussed with awaken :)