When does Romantic Loves end and the Powers struggle begin?

It's impossible to define precisely when these stages occur. But, for most couples there is a noticeable changes in a relationship about the time they make a definite commitment to each other Once they say "Lets get Married", or Let's get Engaged," or Let's be a primary Lovers, even though we still see other people," the pleasing, inviting dance of Courtship draws to close, and lovers begin to want not only expectation of need fulfillment.