Funny question in a way for me, because I love two people, and the feelings are so different.
I used to think the monogamous thing was the way to go. You find someone who you can be yourself around and trust and want to be close to. I found that. I've been in that relationship for almost 20 years. He's so very handsome, and attentive and funny and smart and caring.
Then, I met someone else who fed a different need, and I love him too. He's gone now, but for the time he was here, he made me feel worthy of love. Like, his desire for me made me feel beautiful in a way nobody else has ever made me feel. He was charming, and probably the most handsome man I'd ever seen. He was really sexy. He's brilliant but in a dark way and he was the keeper of my secrets.
I love them both, and would likely die for them. With one gone, I'm half a person. So, to answer your question, love is a couple of things. It's being with someone who makes every place feel like home and you are safe. And hopefully you do that for them too. But I know I love the other person too, because even though every day I wake up in tears, he needed me to let him go and I did. I loved him enough to give him what he wanted, which was to be on his own. He's happier without me. It's so very painful, but I did it. And I think that has great meaning.