If we believe in God and we believe that God is love then we have to question what exactly love is. Because if God really is love then love acts in some strange ways or so it seems. But first, can we accept that there was no real idea of love outside religion until recently when secular thought borrowed it and made it its own? But secular thought interprets love or compassion as a universal, equally applicable to everyone which doesn't make sense because only a universal God can really love universally. This tells us that the secular idea of love is not actually love at all. It's just a theory about love. And love as a theory is meaningless. Love cannot be reduced to an ideology. At least, it can but then it is killed.
If God really is love what then is this love? It cannot be something that wants to make everyone happy all the time because that is not how things are. So, if we accept that God is love we must also accept that love involves suffering or, at least, acquiesces in suffering. It is not just about being empathetic or compassionate but something a lot deeper and more mysterious than that.
I think we can attempt a definition and say that love, spiritually considered, wishes for the increase of good in the loved one. It doesn't just want happiness. It wants goodness and truth and it wants them to be established in the person loved. Now, this leads us to the critical question of what are goodness and truth? Is it good always to remove suffering? Then God is not good. Is it good always to bring joy and peace? Then God is not good. We have to explore further.
You see, we can't understand love without a proper metaphysics. Everything comes down to the matter of first principles and what a human being actually is. If you don't understand that then you cannot understand love and how it works in the world. Love can only be a spiritual thing because it depends on the unique individuality of the one loved. Secular thought which does not recognise God denies spirit and is on that account materialistic but there is no individuality in materialism. We are all just the product of natural forces with no real core identity. Individuality has to be a spiritual thing if it is real. There can be no love without spirit and so there can be no love in a world without God.
The good that love seeks to increase is spiritual good. We don't understand this. We understand material good but to seek to increase material good will often work against spiritual good because it will obscure, or even supplant, it. Spiritual good relates to our reality as spiritual beings and so it seems that really to understand love we have to see ourselves as spiritual beings and know what that means. What it chiefly means is loving the true good which is God. From this love flows all other love.