@Jeruba I see it differently.
I think it’s difficult to predict where a relationship is headed. I mean really, how good are we at predicting where our individual lives are headed! But a relationship?
So to me, if it’s not good now, fix it or go. If it is good, then you’ll just have to wait and see. You can’t know where it’s going.
I knew a couple who married with him wanting a family and her knowing she never wanted to have children. Ten years later they had three. I knew a couple who married despite religious differences – he Jewish, she Catholic. Ten years later, she converted so that they could take their children to Israel to see his parents. And she kept a kosher house after that – for herself not for him. I knew a player who’d been with (according to him) a thousand women. But he met and fell in love with a women (who already had kids) and he became a committed family man. I’ve known people who thought they were on the same track until one of them turned out to be on a tandem with someone else.
When OP says, “I’m not sure about it” I’m thinking things aren’t quite right. So I go back to rule 1: fix it or go. Otherwise, smile for the camera!