Despite being together for years, he still didn't understand what Nubsib saw in him.
Gene wasn't what people would call beautiful or handsome, with luck he would be told that he looks average.
So he didn't understand why Nubsib always called him the most beautiful person he had ever met.
No matter how much Gene tried to find what Nubsib found beautiful himself, he just couldn't.
Maybe it came from the years he spent all alone and how no one seemed interested in him which affected his self-esteem but Gene just didn't consider himself good looking.
But Nubsib seemed to have a sixth sense to know when Gene was thinking about this as he would force Gene to be in front of the mirror in just underwear as he told him every little thing he loved and considered beautiful on him.
Gene may never believe he was beautiful but Nubsib would always make him feel loved and feel beautiful in those moments and that was enough for Gene.