What exactly is LOVE

I'm not sure if i have posted something like this before. But what the heck. Maybe my views have changed a little since the last time i've posted. And maybe not. But for what it's worth, what the heck. I'll post something that i've been asking myself for the longest of time. What exactly is love. And when and how do you know that you are in love. And does love actually have a defining form? Like how do you know you are in love. Is it the butterflies in your stomach? Is there a tune that goes on in your head? A picture that is being painted in one's mind?
And how big is the gap when one is in love? Does it matter if the person is younger then you? Older then you? By a year, 5 yrs, 20 yrs? What does it matter? And at which point do you know its not love for a platonic friend but something much much more?
And does gender really matter? When it boils down to love, does it really matter whether its a guy or a gal? Does it really matter that sometimes, people don't conform to society's expectation? Take for example, a 20 plus year old person dating a 60 yr old man. Would that conform to society's expectation? Age gap too wide? Not natural? Then how about a girl-girl or boy-boy relationship? Lack of any age gap, but still equally unacceptable by society's standards. Now what would be acceptable? And when it boils down to it all, can a person really separate all the feelings into categories or friend, lover, potential marriage partner, buddy, just girl friend, just boy friend, stead boyfriend, steady girlfriend, and the endless other streams of categories they have in this time and age.
Forgive me for being naive here, but isn't it all just too complicated to make of this one simple feeling and process? I mean after all, isn't love just meant to be love? Companionship with a person. Being totally comfortable, being your true self with no fear of judgement? Endless conversations, or just comfortable silence? Just hanging out and chilling out and spending time together not worrying about anything, or worrying about things together? Then how is this different from being a best friend to someone? How is this different from secondary school where our best friends were the people who offered us companionship after school and at home via the phone, through endless conversations, or even just hanging on to the phone and not talking with comfortable silence? And one can screw up one's life totally and not have any fear of repercussions of a best friend judging you, or looking at you with tinted glasses from that day forth.
You know, this isn't easy for me. I've struggled with it for so many years now, and the age old question still bothers me. Maybe it doesn't bother me. Maybe over the years, i've never quite changed my stance about love. I still believe that all you have to do is to be comfortable and happy. And it really didn't matter who you were dating and who you were comfortable with and not comfortable with. But then how do you know its not a crush and that it is really love?