I don't have eco living nor get together, and this just happened to me as well.
I wouldn't say I should have expected them to get engaged.
I'm my situation the the, now engaged couple, lives apart, but they have a child together. The child lives with the mother in my household. The guy, who is the father of the child, called THE CHILD says the thing about the ring in the bag. I answer as any child who loves mom and dad would, I ofcourse say that he should say yes. And then, voila. I get notification that they are now engaged. Not part of my plan..
Of the expansion packs I only have pets, get to work, university and get famous.