It very depends much on who and who I guess. But perhaps JC
students are much childish at their stage of life and probably are
getting a relationship just because of 'play play' attitude and
simply because it is quite 'in'. (I was a JC student in SAJC).
After JC guys goes into the army and seldom gets to see thier girls
except weekends. At the same time the girls get to know more guys
in their universities, providing them with more choices.
Of course I personally have friends who manged their relationship
till now but they are the much minority.