I don't disagree at all.Yes but her needs for a relationship means will change quite a bit more so than if he/she was older.
What he/she thought she wanted in life at 16 is way different than what it is at 25 and later. By that point he/she is more settled as to who a good partner would be. So the fundamental definition of the relationship doesn't change once you reach maturity.
There's a reason over 90% of teenage marriages fail.