I feel compelled to write this as I don't want any confusion between me and someone I truly respect.
I feel that all to often we as a society confuse or don't understand the difference between love and lust for reasons that I won't get into in this post.
To me lust is all about the 'I'. I want this thing, or I want to be with this person. It can be possessive and worrying only about how we feel in the moment. This is when it is taken to the extreme, and it doesn't necessarily need to be a bad thing as we do need some desire to want to be together.
If lust is all about the 'I', what is loves focus? To me love is all about 'them.' It's about the ability to take the 'I' out of the equation and being able to ask what is best for that person you purport to care about. It's about being honest with yourself, and respecting them enough to care what is best for them. Respecting their wishes even if it's not what you want.
There also needs to be a love of self and the ability to recognize that the object of our desire is not always the best thing for us.
In any healthy relationship there needs to be a balance between love and lust. Love is not lust and lust is not love.