Craig is deeply heartbroken due to his break up with Tweek because of a certain situation that involved Tweek moving away. Ever since then, things began to happen, bringing Craig closer to a person he never expected to be with.
⊹₊ ⋆Badly written & rushed⊹₊ ⋆
After Stan and Wendy break up yet again, Stan starts hanging out with Craig.
As their friendship continues to bloom, so do their feelings for each other.
Craig realizes it early on, as he enjoys having Stan around for company. Stan on the other hand, struggles with understanding how he feels about Craig while he tries to move on from Wendy for good.