When our love is in the interest of Allah Subhanahu wa Ta’ala, we either love others for their “hearts” or their “deeds.” 
For instance, when we love or appreciate someone for their hearts, it is because of their intimate connection with the Almighty One. This consequently leads us to loving His Prophets, Messengers, and all of His creation.  
On the other hand, when we love someone’s deeds and the good they do for the sake of Allah (SWT), we respect and defend them according to their actions.
In both cases, we don’t love someone because we know them very well, or because they bring us a direct benefit, or even because they have a nice appearance. Rather, we love and support them because of their efforts to please Allah Subhanahu wa Ta’ala!
This love is an emotional state that is indescribable in words. That’s why when we love someone enough to marry them, we want it because we want to elevate our Iman that brings us closer to Allah (SWT). And if they love us back with similar emotions, it’s also a means to remember Allah (SWT).
May Allah (SWT) bless us with the most righteous people in our life who increase our Iman and lead us closer to Jannah. Ameen.