He wrote a goodbye later, before he wrote love later, because he knows there might be a day come when he'll quit or leave
It might be cuz he knew, one day she will lose the light for him and he won't be able to write latters which she would actually read not just see. And perhaps because of that, he wrote a goodbye latter because it was his way to say to himself "be prepared, world never liked it when you smiled" "world takes what you love not by force but by drop off time, slowly and painfully"
If it is his way then I wonder what kind of life he lived to come to this conclusion, where he accept the goodbye even before he wrote the latter of love















