I’ve seen immature people become menstchen after getting married.
There is a difference between immaturity and bad middos which a 75 year old person can have as well. Bad middos can have a detrimental effect in marriage, while being married and having kids make MOST people mature quickly.
When talking about life experience, how is someone supposed to have marital experience if they were never married? One who has experience in some areas in life doesn’t necessarily mean that they are experienced in all areas.