Does marriage mature

My brother is a 22yr old man who’s loves to drink with his buddies and is about as mature as a 5yr old also Cheating on his almost wife (his business not mine) BUT he’s getting married next month. He just starting living with this woman. Do you rlly think this woman is going to straighten him up after the wedding or no since they’re living together??? (theve been dating 3yrs & he hasn’t changed yet)