Good evening everybody!

This is going to sound crazy but for the last week and a half I have had this song stuck in my head that I heard in an Express store in the Outlet Shops here in El Paso, TX. I was shopping there just killing time and normally I don't pay attention to what stores are playing but this song really stood out. It was a collaboration and the main singer is a gal who kind of sounds like Taylor Swift and the repeating line which I assume is part of the chorus she sings "when I think about us" or "thinking about us". Then after she sings a couple versus this guy gets on and starts singing and then she finishes the song.

The song is about a failed relationship and she can't help but be reminded about it in everything she sees and does. To me I really thought the female singer was Taylor Swift but after scouring all of her music I guess it's not her. Can anybody help me? It has to be a fairly recent song in the last couple of years and the music is a very serious pop sound.

Can anyone help me identify the song?