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.

 وَمِنْ آيَاتِهِ أَنْ خَلَقَ لَكُمْ مِنْ أَنْفُسِكُمْ أَزْوَاجًا لِتَسْكُنُوا إِلَيْهَا وَجَعَلَ بَيْنَكُمْ مَوَدَّةً وَرَحْمَةً ۚ إِنَّ فِي ذَٰلِكَ لَآيَاتٍ لِقَوْمٍ يَتَفَكَّرُونَ. ( Quran 30:21)

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.

From this beautiful ayah we learn that it is Allah who puts love and mercy between the hearts of any 2 people. If you are in a situation where you cant seem to gain the other person's love , affection or mercy, then this ayah is for you. to comfort your soul. It is vital to remember that even if tried everything in the dunya to win another person's heart, we cannot until Allah puts mercy and love in their hearts for us.

For people who reflect will realise that 2 people who dont know eachother and perhaps have massive differences in their characters and also are complete opposites of eachother, yet end up loving eachother and having immense mercy for eachother. How does this happen? It is Allah alone who places that in their hearts. 

To have inherent love and mercy from someone who we really want us to show us these emotions is great blessing of Allah which we always need to be thankful for. In another ayah we learn , 

وَاعْتَصِمُوا بِحَبْلِ اللَّهِ جَمِيعًا وَلَا تَفَرَّقُوا ۚ وَاذْكُرُوا نِعْمَتَ اللَّهِ عَلَيْكُمْ إِذْ كُنْتُمْ أَعْدَاءً فَأَلَّفَ بَيْنَ قُلُوبِكُمْ فَأَصْبَحْتُمْ بِنِعْمَتِهِ إِخْوَانًا وَكُنْتُمْ عَلَىٰ شَفَا حُفْرَةٍ مِنَ النَّارِ فَأَنْقَذَكُمْ مِنْهَا ۗ كَذَٰلِكَ يُبَيِّنُ اللَّهُ لَكُمْ آيَاتِهِ لَعَلَّكُمْ تَهْتَدُونَ

And hold fast to the rope of God, altogether, and do not become divided. And remember God’s blessings upon you; how you were enemies, and He reconciled your hearts, and by His grace you became brethren. And you were on the brink of a pit of fire, and He saved you from it. God thus clarifies His revelations for you, so that you may be guided.

Reading this ayah makes us realise how Allah is the one who changes hearts. He tells us here that he reconciled the hearts of the tribe of Aws and Khazraj  present in Madinah during the time of Rasool SAWS who were previously enemies to one another and even fought many battles against each other. It is by his grace that people love one another and have mercy upon eachother. There is no other answer to this. Allah asks us to stay united and not divided in order to attain this love for one another. And the key point which is to hold onto the rope of Allah in order to receive this great blessing of love and mercy between one another. This means growing closer to Allah (SWT) and his deen through the study of the Quran. Because studying and understanding and implementing the Quran's teachings automatically make us more merciful and gracious towards one another and this in turn brings down the great blessing of Allah- his mercy. When 2 people grow close to one another after studying the deen , it is because they receive the blessings from studying Allah's book and also the study helps them to modify and improve their moral character , thus enabling them to forget differences and forgive mistakes and have patience with eachother.

If you or any family member, friend is going through a time where they are finding a relationship that is straining or not working out, remind yourself and them that it is in Allah's hands alone. They need to make intense dua for Allah to place mercy. They might also need to be really patient during this process. Because sometimes these are tests from Allah to increase our ranks and test our faith in him. Dont despair in his mercy. Have hope and make this dua constantly.

اَللّٰهُمَّ اَلِّفْ بَيْنَ قُلُوْبِنَا، وَأَصْلِحْ ذَاتَ بَيْنِنَا، وَاهْدِنَا سُبُلَ السَّلاَمِ، وَنَجِّنَا مِنَ الظُّلُمَاتِ إِلَى النُّوْرِ، وَجَنِّبْنَا الْفَوَاحِشَ مَا ظَهَرَ مِنْهَا وَمَا بَطَنَ، وَبَارِكْ لَنَا فِىْ أَسْمَاعِنَا، وَأَبْصَارِنَا، وَقُلُوْبِنَا، وَأَزْوَاجِنَا، وَذُرِّيَّاتِنَا، وَتُبْ عَلَيْنَآ اِنَّكَ أَنْتَ التَّوَّابُ الرَّحِيْمُ

O Allah! Put affection amongst our hearts, set right our matters between ourselves, guide us to the ways of peace, save us from darkness towards light, save us from all kinds of indecency; the apparent as well as the hidden, and bless our hearing, our seeing, our hearts, our spouses and our children, and turn in mercy upon us. Indeed Your are the One who greatly Accepts repentance, One who is repeatedly Merciful. (Al-Hakim)