Engaged marriage is not of the reasons why people divorce. It's highly depends on mindset. In my country most of the people do engage marriage and divorce rate is not so high. Those people goes for divorce who have not mentality to balance & sacrifice, (most cases). In fact in love marriage the divorce is a very common thing. There are many things to consider. So I don't agree with the point.
Sex before the marriage is not supportive because it's a thing people (male) will misuse greatly and many women may suffer a lot for the sex before marriage and it's applicable in those county where marriage is a requirement. I don't think in Nigeria it's not a good idea. Will you like it if your women sex with others because of past relationships? In my case I won't like it.
I am sorry if my word sounds offensive. I just shared my opinion.