They need to realise that nobody is perfect and infallible, so if their partner does mistakes that annoy them, they also do some serious mistakes which annoy their partners also. If they start avoiding and overlooking mistakes of each other they will enjoy their lives while living together.
Knowledge is power.
small drops make a mighty ocean
In a family either it is between father and children or mother and children or wife and husband, they will have some affection due to blood relation and living together. So they may adjust with each other and try to live in a friendly way. But when there are financial inequalities among them there will be a rift. In my childhood days, I have seen many families getting separated due to these financial matters only.
But the present days are different. Financially there is no dependence on each other and every child of a couple are doing will and hence their friendship is continuing. They are in separate places and they will be meeting once in a while only. That is making the relations strong.
If both the parties involved in the relation maintain a friendly nature and try to accommodate others also the relation will continue I feel.