As far as I am concerned there is. If you are having sex just to have it, it can get very old quickly. There needs to be time out of the bedroom (or where ever you are having sex) and then you need to spend alot of time building on your relationship.
If the relationship exsists only when having sex, it will fail and whomever is feeling like they were in love will be sorely surprised that the other person has little or no feelings for them because all the was built was a relationship of gratification.
Take a break away from sex and start talking, you will quickly know if there is any substance to your partners feelings for you.