One of many reasons we need relationships with others is actually metaphysical -- it's almost impossible to stay in the real on our own. We rely on others to know the real (the truth) from imaginary... to keep us sane, basically.
Otherwise, it pays to understand things and people, and that's what true love is, first and foremost -- love is understanding. And, so unconditional -- because understanding is! Tho it'd be more accurate to use "compassion" in this context -- "love" has many meanings, not all of them positive.
Oh, and that's why "love you enemy", as Jesus would put it -- 'because "know your enemy", as Sun Tzu would put it in "The Art of War" -- can't really know anyone unless have compassion for them. And while Sun Tzu was primarily concerned with military advantage, the most tangible benefits of having compassion to our enemies is it's capacity for de-escalation (which was also Sun Tzu preference).
And that can go a surprisingly long way. It might not be obvious, but in any fight, the opposing sides are not actually fighting each other. They are on the same side, and they have a common enemy -- their own fears. That's why we should think twice before hurting our opponent, as we will be helping the real evil.