Love is the attempt to form a friendship inspired by beauty.

Attraction starts things and friendship is what has to be built afterwards. What makes a long attachment survive is largely what makes a good friendship: liking their company, being interested in what they think, wanting good things for them when there is nothing in it for you. Beauty opens the door and does not furnish the house.

Worth asking of any close relationship whether you would choose this person as a friend. If the honest answer is no, that is important information. And if it is yes, tend the friendship part deliberately, because it is the half that lasts.