In my opinion, I think that Page and JJ have come along wasy and are doing a great job portraying teens in love. They are suppose to be 18 as they are going off to college. If you remember the Belle, Shawn and Philip days they seem to be on par to the time that they went to Salem U.
You cannot expect them to act like adults, but to me they seem realistic.
Of course, the show has changed since the days of Tom and Alice, cause life has changed and things are a lot more acceptable today. (right or wrong) However, soaps have ALWAYS been full of affairs, divorces, pregnancies, etc.