Rihanna - Stay is one song that I could hear over and over and over and never get tired of hearing it. It comes on the radio all the time, on many different stations and it doesn't seem to matter how many times I hear it in a day I don't mind hearing it again.
I heard somewhere that this song was voted the number one break up song of the year. I have never thought of it as a break up song. To me it's about two people who don't want to be in love but are and are trying to come to terms with it. I think that is what the whole "not really sure how I feel about it" line comes in. I don't want to feel this way, but I do, and since you are helping to fix me and I'm fixing you, you may as well stick around. Even if we don't really like it :-)
Regardless of how you interpret the song, if you think it's a break up song, or if you think it's a song about not wanting to be in love, it's still a great song. Even though it has been played out over the past year I still just can't get enough of it.
I stumbled across Demi Lovato covering this song and fell in love with her version too. It's goose bump good and worth listening to.