Similarly "Meines guten Freundes" works in the context of "the house of my good friend" and "Meinem guten Freund" works in the context of "I offered a beer to m

Similarly "Meines guten Freundes" works in the context of "the house of my good friend" and "Meinem guten Freund" works in the context of "I offered a beer to my good friend".