He Had the Thought Bubble!

So, do you totally plan out your Sims' lives or do you also include their thought bubbles? I ask, only because this young couple will eventually marry. He just aged up to YA, she will be aging up in a few more Sim Days. As he's bidding her good evening after his birthday party, suddenly in his thought bubble is a diamond ring! Question is, do I have him pop the question, or leave it for a little longer, say when they're at Uni, or after they graduate?

Any thoughts?

How much is your gameplay influenced by a Sims' thought bubbles?