If people are to live happily together, they will have to accept that, because of their different backgrounds, there are, as to matters of taste, bound to be different likes and dislikes. Further, it must be appreciated, that to deal with people -- let alone to live with them -- one is naturally vexed at these differences; and just as naturally, there is a tendency for one person to drive their own tastes and opinions onto another. This can be the source of much trouble in a relationship. So, the main rule for living together is: if you cannot rejoice in your differences, tolerate them in silence. Here are some others.
Do not interfere unreasonably with the other, do not ridicule their tastes, do not question and re-question their resolves, do not indulge in perpetual comment on their proceedings.
Avoid stock subjects that are known from past experience to give rise to disputation. These subjects are readily recognized by people especially after they have lived together for an extended period of time; certain set topics, around which, from frequent dispute, there is such a growth of angry words, mortified vanity, and the like, that the original subject of difference becomes a standing subject for quarrel; and there is a tendency in all minor disputes to drift down to it.
If you would be loved as a companion, avoid unnecessary criticism upon those with whom you live. One of the most provoking forms of the criticism above alluded to is that which may be called criticism over the shoulder. Acts or words which amount to disclaimers, such as: "Had you asked me," or "I told you so," or "Had you listened to me." Recall the poetic words of Lord Byron:
Of all the horrid, hideous notes of woe,
Sadder than owl songs or the midnight blast,
Is that portentous phrase, I told you so.
(Don Juan, Canto XIV, st. 50.)
Do not let familiarity swallow up all courtesy. As Oliver Wendell Holmes has said: "Don't flatter yourselves that friendship authorizes you to say disagreeable things to your intimates. On the contrary, the nearer you come into relation with a person, the more necessary tact and courtesy become. Except in cases of necessity, which are rare, leave your friend to learn unpleasant truths from his enemies; they are ready enough to tell them. ... Neither make too much of flaws and occasional overstatements. Some persons seem to think that absolute truth, in the form of rigidly stated propositions, is all that conversation admits."
Do not make hasty and uncharitable comments. It is easy to make such unwelcomed comments; either because one is in the heat of a quarrel, or because one would like to be quick or witty in company.
Intimacies shared, sexual or otherwise, should not be shared with any one else, even friends or relations.
Give advise only when asked, and, it must be remembered, advise can only be given about anticipated events in the future.
Do not place blame, as Confucius said, "It is needless to speak about things that are past, things that are done, it is needless to blame."