As a general rule, yes. However, if you started dating at 18-21 then I think a larger interval between starting to date and the man proposing is not only reasonable, it's prudent.

I've only seen one case of a man happily proposing after the 4-5 year window that worked out. My aunt and uncle started dating when she was 22 and he was 30. They dated for 8 years, and she got to the point where she realized she wanted kids it was time for her to move on if he wasn't interested. She didn't give him an ultimatum-she just set an end date in her head, and if he hadn't proposed by then, she was going to leave the relationship.

He must have sensed something had changed because he proposed within a couple months of her internal deadline. I will say-an extenuating factor was that his own parents' marriage was terrible, and his mother was overbearing and critical. I think he may have set out into adulthood with plans to never get married. My aunt on the other hand might be one of the nicest people I've ever met on the planet, and I think he realized keeping her was worth a change to his plans. They've been happily married for 30 years now.