When did the die in your relationship? Also did you fix it if so how.?

I have dated this girl for 3 years and people say and it feels like we are married. used to be fantastic but now i only get it once a month if i am lucky and when i do it feels like its out of obligation. i have tried the romantic route, the goofy route, mages, hot bath water. I have tried it all to set the mood but we can not get our flare back. How do i get it back, or when is it time to move on? Sorry if there are typos