Ar-Rum 30:21
The verse builds a triangle from three words: sakīna, mawadda, raḥma.
وَمِنْ ءَايَـٰتِهِۦٓ أَنْ خَلَقَ لَكُم مِّنْ أَنفُسِكُمْ أَزْوَٰجًا لِّتَسْكُنُوٓا۟ إِلَيْهَا وَجَعَلَ بَيْنَكُم مَّوَدَّةً وَرَحْمَةً ۚ إِنَّ فِى ذَٰلِكَ لَـَٔايَـٰتٍ لِّقَوْمٍ يَتَفَكَّرُونَ
And of His signs is that He created for you mates from among yourselves, so that you may find tranquility in them; and He planted love and compassion between you. In this are signs for people who reflect
Ar-Rum 30:21 · Translation: talal-itani
Image
The first is a stilling; the second a mutual attraction and love; the third a compassion that shields the other. Meeting a spouse is not an outer contract but an inner recognition, "min anfusikum" — "from yourselves." The verse closes with a reservation: this is a sign — for a people who contemplate.
Observation
In the psychological literature the concept of "attachment" names the contribution a secure closeness makes to both emotional and physiological regulation; clinical studies document that the presence of a trusted other dampens the stress response and that secure relationships support mental health over time. The verse's image of stillness can be thought alongside this phenomenon — the verse proposes no biochemical mechanism; it gathers a lived fact and calls it a sign for contemplation.
Exegesis
Classical exegetes identify the most striking element of the verse as the verb "li-taskunū": al-Rāzī notes that it carries at once the senses of "taking refuge in one another" and "finding rest in one another." Elmalılı draws the distinction between mawadda and raḥma: mawadda is a mutual pull, while raḥma is the attitude the strong turn toward the weak, the well toward the ill, the young toward the old — roles that change with time. The verse spreads the pair across a lifetime; it wraps the different seasons of that life in both love and mercy.
Sources
Tafsīr: Fakhr al-Dīn al-Rāzī, Mafātīḥ al-Ghayb; Elmalılı Hamdi Yazır, Hak Dini Kur'an Dili. Science: standard clinical-psychology literature on attachment theory and the effect of close relationships on physiological-emotional regulation.