I think that the girl that this song is about is in an unhealthy relationship (whether it be anything from abusive, to he's just not "the one" and doesn't understand her) but for whatever reason (expectations, fear of change etc.) she is still with this guy.
However, the singer has feelings for this girl and this girl seems to have feelings for her back, and although it makes sense for them to be in a relationship instead, they're not. So although this girl is always around and they even have 'moments' together ("I look in your eyes, and they're not cold"), ultimately they are not a couple, and although the singer realises that it is probably not the best for her to spend time with this girl, she decides that it's worth it and she will stand by her (or rather 'stay with' her).
I think that the girl that this song is about is in an unhealthy relationship (whether it be anything from abusive, to he's just not "the one" and doesn't understand her) but for whatever reason (expectations, fear of change etc.) she is still with this guy. However, the singer has feelings for this girl and this girl seems to have feelings for her back, and although it makes sense for them to be in a relationship instead, they're not. So although this girl is always around and they even have 'moments' together ("I look in your eyes, and they're not cold"), ultimately they are not a couple, and although the singer realises that it is probably not the best for her to spend time with this girl, she decides that it's worth it and she will stand by her (or rather 'stay with' her).