> What I object is to consider that the one who leaves is automatically the selfish one.

Well, I never implied or assumed any selfishness on part of either imaginary fictional persons that I was referring to.
I didn't even consider selfishness; It's too subjective.
If we want to discuss selfishness, it could be considered selfish to expect either partner to maintain contact, love and fidelity despite the distance.
I was just pointing out that it's similarly unfair to expect someone to uproot themselves.