I agree with you that a celebration of the relationship is in order, at least when new life is getting ready to show it's face. But my thoughts are that marriage or not, it's still easy to walk away.
I'll take my family as an example: My father has 2 brothers and 2 sisters. Every one of them has one or more children. One of my uncles is still married to his original spouse. The others are divorced and now with another partner, so the divorce rate in my example equals 75%.
This is not a special case, the divorce ratio in my country (Norway) is quite high. But fewer and fewer are getting married.