In other words (that aren't as British sounding), the longer a couple's been together, the longer they'll be engaged. And vice versa; the shorter the relationship at the time of the proposal, the shorter the engagement period will be. We developed this groundbreaking theory based on very extensive research and vigorous scientific observation (or perhaps by gossiping about our own and our friends' relationships [no, it's definitely the scientific thing]).
Has anyone seen our theory in action in their own relationship, or in their friends' relationships? Or does anyone want to challenge the theory? (We dare you!)