Bob has a point.

Having sex at 13yrs old is perfecly normal,in fact girls in most cases reach puberty around that time if not earlier.Puberty means that their body is now ready for sexual reproduction.As long as she had given her consent,there is nothing to worry about.Of course in the eyes of the law the legal age is 16 in some cases even 18. As much as I would like to agree with the law am' afraid to say is compleately unrealistic.
In fact laws are'nt always in accord with human nature and is some cases they go even against it.Sex is a natural human activity and should not be condemed but embrace it entirely.We can go on deceveing our selves and continue to view sex as a taboo or choose to come out of the ignorance and self deception and start to see things as they really are.Laws are more concerned with control and suppression rather than the actual health and wealth of the individual.

ok, so your friend is having sex with an older man! What is really the concern is what lead up to this and why is it continuing? I would like to find out if there are issues at home, with the family and has this teen been abused? never prejudge unless you have all the facts and even then,"Judge yea, yet be judge"...so in other words, who are we to judge someone, unless we wish to be judge...help the girl and not lower her self esteem...