You are including infatuation and romantic love in with the love that endures over a long time and many trials. Love has so many forms as to be almost infinite in variety. It can be one sided, as a child who has rejected you. It can be from afar, as a best friend from childhood who has taken a totally different path in life. It can of course be happy and full of like, as when two people who got past romantic love decide they still want to be together.
One sided romantic love isn't love. It's just infatuation.
I agree that when young we tend to have an ideal of the one we are in love with, and the odds aren't in favor of that kind of love lasting. Love takes time, pure and simple, and it usually takes a lot of compromise. You trade the faults for the comfort of knowing that this person has stood by you. You take the whole package, and your partner takes you the way you are too, and you try to laugh off each other's faults, and that's love.