Well even in marriage men and women have to be 'chaste' that is to not cheat and not be watching too much porn , making the other feel hurt. So there is chastity to a degree in marriage.
The key about sexuality is to learn how to deal with it and keep it under control. That is to lean not to abuse it, or to hurt anyone etc.
I think there are ways to deal with it, as many know it's okay to masturbate and stuff like that. As far as I know that's okay.
I think a reason why that rule was implemented was to prevent children from being born without two parents....back then there was no birthcontrol.
Today these is birthcontrol.
I think it depends on the individual what to do and what not to do. Some will wait until marriage some will not.