No, it's realistic. It is basic logic to say "I can observe this, or its effect, therefore it must exist". I am not fully sold on quantum mechanics and don't really know enough to speak of it otherwise.
Love is actually a cascade of chemical reaction in the brain that are really well resolved. Lanturn314 in is neuroscience at Johns Hopkins and I will refer you to her on that matter for accuracy's sake, but I do know off the top of my head that chemicals like Dopamine and etc are involved. Just ask her the chemicals and reactions and etc involved in love, it's really quite simple to understand I am just forgetful of such things.
Trying to invoke love is still kind of god of the gapish of you. How personality manifests is a great big gap, but I'm confident it can (and will) be resolved. It exists, it can be measured, therefore we can understand it.