Well, sure, love is the result of chemical reactions in the brain. But why on earth would that mean it isn't real?
It's all a matter of perspective. The human race evolved altruistic instincts in order to survive. If a man is drowning in a lake, and another man is standing on a dock, the man on the dock most likely feels compelled to help. Why? He gets nothing from this. There is most likely no real reward. In fact, he may be putting himself in danger by helping the drowning man. It's because he's compelled to, by chemical reactions in the brain. He instinctively understands that, if he were in that position, he would want someone to do the same for him. Love, empathy, team work, and intelligence is what has allowed our race to survive. You can say that it's just the result of chemical reactions in the brain, but you can say that about anything. The Aurora Borealis is just the result of atoms from the sun hitting atoms in our atmosphere. The sun, which gives us life, is just a ball of hot gas. The most beautiful book you've ever read is just words on a page. You can say that love is just a chemical reaction in the brain. I prefer to think that love is literally coded into our DNA.