Aside from nostalgia, why on earth does Ned seem to love Robert so much?

Ned is a stern man, unyielding in principle to the point of being stupid and unable to adapt, and holds his honor high.

Why, then, does he have such affection for Robert?

Robert Baratheon is a belligerent, drunk asshole with a rage and violence problem. Honor seems to matter very little to him.

Knowing what we know of eddard, he should be disgusted by Robert. I can't imagine he'd have any respect for a man like that.

Is it really just nostalgia for their childhood? It seems like more than that, but I dont quite understand it.

Just blind loyalty from Ned?