The Prophet (Pbuh) said...
The Prophet (Pbuh) said: The one with the best temper, the one who is the most persevering, the one who helps his relatives the most, and the one who is most fair to others regarding himself. [Bihar al-Anwar , v.77, p.58] Nobility and a good temper are so valuable that the noble Prophet of Islam (Pbuh) has declared it to be the reason for his appointment to the Prophethood. It is certain that I was appointed to perfect your good temper, and nothing else.
[Mizan al-Hikmat , v.3, p.149] I was appointed to perfect your good temper. [Ibid] Being good-tempered and having good morals are rays of God’s attributes, the way of the Prophets and the Immaculate Imams and the cause of goodness and blessings for the one with these attributes. A bad temper and foul behavior are satanic and are the causes of disruption of life, insecurity, separation, and hatred of people; and will ruin the life here and in the Hereafter.
I will refer to several points which should be adhered to by any couple in order to strengthen their relationship, and continue their love and affection. I hope that God the Almighty will adorn us all with a good temper and morals and help us avoid bad morals. Love and its Expression God has established love in our hearts as husbands or wives and recognizes this to be one of the signs of His Existence.
This fact is a manifestation of the importance and extent of love and especially the love and affection of man towards a woman. And among His signs is this, that He created for you mates from among yourselves, that ye may dwell in tranquillity with them, and He has put love and mercy between your (hearts): verily in that are Signs for those who reflect.
[Holy Quran: Rum 30:21] This love and affection blossoms early in marriage and even before the religious wedding ceremony, and it grows until it reaches its final extent. It is the responsibility of both partners in marriage to maintain this given blessing and this excellent spiritual state of love which is the main cause of happiness and pleasure in life.
This can be done by mutual support, being good-tempered, forgiving, cooperation, reasonable expectations, mutual respect, avoiding arguments and fights. The couple should avoid what might harm their loving relationship.