It's expected that you be gracious towards your in-laws.
John is a newly wed and visiting his wife's family for the first time.
John wants to stay close to his wife.
John spends lots of time with all the different members of his wife's family during the visit.
John tries to spend as much time alone with his wife as possible during the visit while ignoring her family.
John and his wife bond over their, now shared, family experience.
John's wife's family grow to not trust John and their comments about it to John's wife eventually sour the marriage.