How does evil come from love

In truth people are loving – one needs only look at children and see the warmth in which they greet strangers, naively supposing the world is there to return such love

But where do things go wrong?

As always, the Torah actually is the prototype to explain

Why would Kain kill Able his own brother

The answer is clearly there, out of jealousy

The midrash further teaches, that kain was jealous that Able was born with a second triplet

In other words, the reason otherwise happy people who literally have the entire world to themselves get sour, as the Torah described his face – mood – fell, is because people are naturally jealous!