. . .you usually get more comfortable around each other and want to be together more the longer the relationship lasts, not the other way around.

I didn't read any of the above replies yet, so maybe this has been covered already. Sounds to me like it's run its course and it's time to move on.

os·ti·na·to
/ˌästəˈnädō/
noun
a continually repeated musical phrase or rhythm

http://austinato.bandcamp.com

https://www.discogs.com/lists/Favorites-of-2017/332378