There is a thing called the seven year itch. My 5 year relationship recently came to an end and that has lost any passion in it, he would argue and I had no will power to argue back cause I didnt care anymore. However, there was a 4 and a half yer history of violence and abuse to go with that too.
I dont think love happens naturally forever, i think you have to work at it and rekindle that spark. Maybe try a few extra special dates (if you ahvent already) and see if you can see it again. If you dont, at least you had a few nice meals, and if you do it will be like starting the relationship all over a gain.