Lampshaded: Bob: "You know, I honestly can't imagine my life without Andy being around."
Invoked: Andy is subjected to a Stalker with a Crush and to get her to leave explains that he and Bob do everything together, including making him a third wheel on a date and never having him leave their company.
Defied: Andy and Bob realize that the only reason they have remained close friends is because they don't spend all their time together.
Discussed: "You know, sometimes I wish we were as close friends as Bob and Andy are with each other."
Conversed: "You know, I don't think there are closer friends in fiction than Bob and Andy."
Deconstructed: Andy and Bob's close friendship is horribly co-dependent and somewhat unhealthy, and has a deleterious effect on any other friendship or relationship they might hope to construct, particularly of a romantic nature.
Reconstructed: Andy and Bob's close friendship has been the one constant rock that either has had to rely on throughout the struggles, hardship and pain that has characterized their lives up to that point.
Played For Drama:
Andy is emotionally abusive towards Bob, but Bob remains his friend anyway, because they've been friends for so long Bob can't function without Andy.
Andy's wife hates Bob, and Andy leaves her rather than break off his friendship with Bob.