Somewhere in this endless internet I’ve found the most breathlessly poetic answer to this question – sadly not by me 😉 – but by author Jeanette Winterson:
How do we fall in love?
You don’t fall in love like you fall in a hole.
You fall like falling through space.
It’s like you jump off your own private planet to visit someone else’s planet.
And when you get there it all looks different: the flowers, the animals, the colours people wear.
It is a big surprise falling in love because you thought you had everything just right on your own planet, and that was true, in a way, but then somebody signalled to you across space and the only way you could visit was to take a giant jump.
Away you go, falling into someone else’s orbit and after a while you might decide to pull your two planets together and call it home.
And you can bring your dog. Or your cat. Your goldfish, hamster, collection of stones, all your odd socks. (The ones you lost, including the holes, are on the new planet you found.)
And you can bring your friends to visit.
And read your favourite stories to each other.
And the falling was really the big jump that you had to make to be with someone you don’t want to be without.
PS You have to be brave.