Shaykh al-Islam Ibn Taymiyah said in Majmoo’ al-Fataawa (10/129):
Love is a psychological sickness, and if it grows strong it affects the body, and becomes a physical sickness, either as diseases of the brain, which are said to be diseases caused by waswaas, or diseases of the body such as weakness, emaciation and so on.
And he said in Majmoo’ al-Fataawa (10/132):
Loving a non-mahram woman leads to many negative consequences, the full extent of which is known only to the Lord of people. It is a sickness that affects the religious commitment of the sufferer, then it may also affect his mind and body.
Ibn Taymiyah said in Majmoo’ al-Fataawa (10/185):
If a man is in love with a woman, even if she is permissible for him, his heart remains enslaved to her, and she can control him as she wishes, even though outwardly he appears to be her master, because he is her husband; but in fact he is her prisoner and slave, especially if she is aware of his need and love for her. In that case, she will control him like a harsh and oppressive master controls his abject slave who cannot free himself from him. Rather he is worse off than that, because enslavement of the heart is worse than enslavement of the body.
Shaykh al-Islam Ibn Taymiyah said in Majmoo’ al-Fataawa (10/135):
If the heart loves Allah alone and is sincerely devoted to Him, it will not even think of loving anyone else in the first place, let alone falling in love. When a heart falls in love that is due to the lack of love for Allah alone. Hence because Yusuf loved Allah and was sincerely devoted to Him, he did not fall into the trap of love, rather Allah says (interpretation of the meaning):
“Thus it was, that We might turn away from him evil and illegal sexual intercourse. Surely, he was one of Our chosen, (guided) slaves” [Yusuf 12:24]
As for the wife of al-‘Aziz, she was a mushrik as were her people, hence she fell into this trap.
Ibn al-Qayyim said in Rawdat al-Muhibbeen (147):
If love occurs for a reason that is not haraam, the person is not to be blamed, such as one who loved his wife or slave woman, then he separated from her but the love remained and did not leave him. He is not to be blamed for that. Similarly if there was a sudden glance then he averted his gaze, but love took hold of his heart without him meaning it to, he must, however, ward it off and resist it.
Song of Solomon 8:7
Many waters cannot quench love; rivers cannot wash it away. If one were to give all the wealth of his house for love, it would be utterly scorned.
So Jacob worked seven years to pay for Rachel. But his love for her was so strong that it seemed to him but a few days.
1 Corinthians 13:1-8a and 13
If I speak in the tongues of men and of angels, but have not love, I am only a resounding gong or a clanging cymbal. If I have the gift of prophecy and can fathom all mysteries and all knowledge, and if I have a faith that can move mountains, but have not love, I am nothing. If I give all I possess to the poor and surrender my body to the flames, but have not love, I gain nothing.
Love is patient, love is kind. It does not envy, it does not boast, it is not proud. It is not rude, it is not self-seeking, it is not easily angered, it keeps no record of wrongs. Love does not delight in evil but rejoices with the truth. It always protects, always trusts, always hopes, always perseveres.
Love never fails....And now these three remain: faith, hope and love. But the greatest of these is love.
Husbands, love your wives, just as Christ loved the church and gave himself up for her.
However, each one of you also must love his wife as he loves himself, and the wife must respect her husband.
And over all these virtues put on love, which binds them all together in perfect unity.
1 Peter 4:8
Above all, love each other deeply, because love covers over a multitude of sins.
1 John 3:16
This is how we know what love is: Jesus Christ laid down his life for us. And we ought to lay down our lives for our brothers.
1 John 3:18
Dear children, let us not love with words or tongue but with actions and in truth.
1 John 4:8
Whoever does not love does not know God, because God is love.