It's impolite to overstay one's welcome.
Mack has not seen his brother in several years and wants to visit him at his home in another state.
Mack wants to spend time with his brother.
Mack goes to his brother's house for a week visit, where they visit places together and have a great time.
Mack surprises his brother with a visit and stays for a month.
His brother thanks him for the visit and invites him back next summer to stay.
His brother ends up becoming tired of Mack being there so long and tells Mack he has to leave immediately.