When he thinks of unconditional love, he thinks of a rock that never changes, even with whatever weather or processes of erosion its subjected to. It’s not difficult for him to conjure up the image, but it is difficult for him to think that this rock never gets weary or annoyed at all the obstacles it has to face.
He’s pretty sure even unconditional love can get annoyed or angry, but the key is in the fact that it will always exist no matter what.
He thinks of a warrior, coming home from battle carrying nothing but his scars and a smile that speaks more than the sum of everything that comes after.
He thinks “forever” lasts longer than “infinity” and “always”, because one is more like a number and the other is too one-dimensional. “Forever” speaks of time, and goes on and on and on like unconditional love that goes on forever and ever.