love ... what is its peculiarity and meaning?

What is love? What is it - attraction physical, spiritual? Or maybe this feeling is different for everyone? Is it possible to fall in love with a person with whom it is not good in all aspects? Or is it not love? Married couples who have been together for more than a dozen years say that love and habit are different, so that the habit does not develop - you need to keep the fire in relationships, to please each other in bed and at home. They also say that it is worth getting married without waiting for this very habit. What do you think? Does love at first sight happen or not?