I fail to see any problem if two humans get romantically involved qnd explore sex together - so long as they are well educated and responsible about all the issues involved and take sensible precautions and are supported in doing so!
The biggest problems usually stem from fear and distance from adults they fear and so get no support and end up stressed and at low ebs getting pregnant or into rebellious moods.
Maybe its better to prevent by support and advice and freechoice than to oppress and limit and restrict and imbue fear into what should be a beautiful life experience?
That would be my feeling - for adults to know how to chat stuff through and give support if the couple feel they want sex together. Sex is nature! Sex is a beautiful experience for both! Pity so many tensions surround it that cant be looked at in a calmer trusting way IMO.
Trouble is lots of families aren't in touch with each other well enough to enable the above but that's likely due to social issues anyhow which tend to replicate - proving that intolerance is perhaps not a solution?