Generally agree, but I don't think the situation is quite as bad as this, for two reasons. First, I agree that stated preferences can change drastically over time, but I suspect that actual preferences are more stable. Second, introspection is difficult and humans are not automatically strategic, so people are both unlikely to have a good grasp of their own preferences and unlikely to reliably take actions to satisfy even what they believe their preferences to be. Life changes that look like they're changing your preferences might just be life changes that help you get a better grasp of your existing preferences or get better ideas about how to satisfy them.

My guess is that the life changes that are most likely to change your actual preferences are those associated with biological mechanisms, e.g. puberty and the biological clock. The ones most likely to change your stated preferences might be those associated with substantial shifts in your peer group, e.g. going to college. Either way, these kinds of shifts both have the property that everyone else is going through them too, so at least they're not weird shifts.