People keep talking about this thing called "love".
Based on all the crap going on in the world, and the horrible things that have happened in the past, I don't see any objective evidence that love exists. And I've never felt love myself, at least not the way it's been described by others.
If one can't prove love exists using the scientific method, and I've never experienced it personally, then to me all this talk about love is just myth, a fairytale to make people feel better about their lives.
Rational grownups have better things to do with their lives than waste time on superstitions. Love only exists if you can prove it does.
What would be sufficient proof? Your own feelings and opinions on an issue aren't proof, they are merely anecdotal and tangential. You may think you feel love and thus know what it is, but a more objective person might call your feelings lust, or fondness. How we feel about our parents, our s.o.'s, our children, and our pets differ so much in quality and intensity, it's inaccurate to throw all those different feelings into one category called "love".
Besides, those feelings you call "love" are all provoked or mediated by neurological chemicals in the brain. Even so, this knowledge won't help with scientific proof of the existence of love. Oxytocin is one chemical supposedly connected to love, but it's connected to other things, too. If you give oxytocin to a person, can you make them fall in love with the person next to them? I didn't think so. That swooning feeling you get when you see someone devastatingly attractive isn't love, as many sadder and wiser people will tell you.
Certain areas of the brain light up when one feels love, supposedly, but the same areas light up for other reasons, too. If you stimulate that part of the brain, will the test subject fall in love with the surgeon?
People can point to all the selfless and giving acts they do for love, or that are done for them for love, but those acts don't prove anything about love. They could be done for many other reasons. Working two jobs to make sure your kid goes to the best private school - Love, or compensatory feelings? Proposing by billboard - Love, or self-promotion? Bringing breakfast in bed - Love, or wanting to get laid? Staying by your sick kid's bed all night - Love, or instinctual drives to secure your gene pool?
Despite the millions of people over human history who have spoken and written about love, and created art, music, and dramas about love, just because we sense a certain affinity with their artistic expressions of what they feel love is, doesn't mean that what they experienced as love really is love, nor that they prove love exists.
One could call love a theoretical construct that benefits society, but that doesn't make it real. One could call longing for love biological, but that doesn't make it logical, rational, and therefore worthy of serious consideration and respect.
Of course, this is snark. Pretty much everyone has felt something unique at one time or another that they immediately identify as love. Love is difficult to prove because it is experienced internally. All the acts we manifest out of love can be interpreted differently by different people. Yet we know love exists and feel no need to prove it quantitatively in order to believe in it.
What happens when you substitute "God" for "love"?