Definition of "love" An intense sense of affection for someone.
Definition of "lust" A strong sexual desire to someone.
If you believe you truly know the person and you have seen their flaws, and still admire them, it is more than likely love. Now don't be fooled, everyone has flaws...even rich people. Being in love doesn't exclude lust
Now with that being in love doesn't exclude lust, but sometimes people confuse the two. Love is not perfect and has imperfections.
It is more than likely lust if you find yourself thinking of the other person as someone who can do nothing wrong. You may be asking yourself "Why aren't we having sex right now" when watching a movie. Lust often has no boundaries as far as being monogamous because it isn't love.