Allah has made an essential part of marriage.

The phrase you provided, 

"أَزْوَاجًا لِتَسْكُنُوا إِلَيْهَا"

 (Azwaajan li-tas-kunoo ilaiha), is part of a verse from the Qur'an that speaks about the purpose of creating spouses for mutual comfort and tranquility. It is often understood as highlighting the harmonious relationship between partners.

This specific part comes from Surah Ar-Rum (30:21), where Allah says:

"And among His signs is that He created for you spouses from among yourselves so that you may find tranquility in them, and He placed between you affection and mercy."