Some folks have put together their "Ladder" theory to explain male-female social interaction. Years ago, I proposed an alternate theory: Let X be the longest period of time you've been dating a given person (in years.) Let Y be the number of times you've been dating (so, if you broke up once and reunited, Y=2). Z = XY
It has been observed, empirically, that in all cases where Z>=10, the couple eventually gets married. Now, it's not a requirement for Z to be larger than 10, but if Z is larger than 10, it *will* happen. There are lots of potential explanations for this behavior (such as the "self-persuasion" that inevitably occurs in reuniting), but that's not important.
What's important is this: for unmarried/marraige-afraid friends of mine, this has been a useful tool. That is, "Gee, I don't want to get married. But if I break up with her before I'm certain we won't get back together, I risk making marraige an inevitability.
Now...as for me, Y was 1 in every case. And Z