Lust = desire
here is the dictionary link
http://www.thefreedictionary.com/lust
Good lasting relationships will never ever by Lust only it is a combination of many factors such as sharing responsibilities.
By the way here is an advice
"If you want your relation with your supose strong stay away from the things which can spoil it"
So now we have the question:
What are the things that spoil the relationships?