-Lasting relationships are those that are built on love - not infatuation or lust. Imagine the person you love in 50 years when they are old and fat. Would that change how you feel about them? If yes, then what you feel now is most likely lust/infatuation - not love.
-Keep in mind that "True love is neither physical, nor romantic. True love is an acceptance of all that is, has been, will be and will not be." (Unknown)