Reason why Zac Efron and Vanessa Hudgens Split

What is the reason why the High School Musical stars Zac Efron and Vanessa Hudgens split? According to reports, Zac Efron called it quits after he realized he is not ready to be engaged.

Vanessa Hudgens is rumored to have pressured Zac to get engaged.

Is this the real story behind the break-up?