Noble or Selfish?

If you love someone, let that person go.

I've heard the maxim above many times before. But more recently, it has gotten me thinking-is it selfish or noble to do that? If you truly love someone, do you love them for whom they are, or whom you are together? If it is the former, then is letting that person go a noble act because you know s/he deserves better, or is it selfish because one is unwilling to try to become that person oneself?

Is it truly noble, that you should choose not to impede on their happiness? But then, why would you not always let them go? Isn't there always going to be someone else? Someone else who fits them in a different way but equally well? As much as I like the concept of "the one" as a good excuse to hide behind, I don't think it actually exists.

Et tu te baladais sur l'avenue avec moi
Tu me comprenais le mieux, pour la plupart
Mais tu ne me comprends plus
Tu parlais cette langue autrefois
Autrefois quand tu aimais moi

Si j'avais dit ces mots clairement en plein anglais
J'aurais aimé que tu comprendrais
Mais quelque soit la façon dont je dis ça,
Tu ne comprendras pas moi